Multi-Layer, Ethylene Polymer-Based Films with High-Density Polyethylene Based Stiffening Layer

ABSTRACT

This invention discloses a multi-layer film for making pouches for containing flowable materials, said multi-layer film comprising generally five layers in order: inner sealant-layer, first interposed layer, the core layer, second interposed layer, and the outer sealant layer. All layers are ethylene-based. The combined thickness of the first and the second interposed layers is in the range of from about 10% to about 27% of the total thickness of said multi-layer film. Similarly, a combined thickness of the inner and the outer sealant-layers is in the range of from about 10% to about 27% of the total thickness of the multi-layer film. The interposed layers comprise high-density polyethylene that has a density of at least 0.950 g/cm 3  and a melt-index of less than 1.05 dg/min.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.61/324,843 filed Apr. 16, 2010, which is incorporated by referenceherein in its entirety.

FIELD OF INVENTION

This invention relates to ethylene polymer based multi-layer films withimproved stiffness and clarity. This invention also relates to a processfor making such multi-layer films, and to pouches for containingflowable materials made from such multi-layer films More specifically,the present invention relates to films that have high-densitypolyethylene based polymers localized closer to the outside surface ofthe multi-layer film so that the multi-layer film not only maintains itsmechanical integrity but also is thinner in gauge than currentlyavailable films. In one aspect, the present invention relates topackaging flowable materials such as milk in pouches using for example,a vertical form, fill, and seal apparatus (“VFFS”).

BACKGROUND

In the VFFS process, a flat web of synthetic thermoplastic film isunwound from a roll and formed into a continuous tube in a tube-formingsection. In the next step, the longitudinal edges of the film are sealedtogether to form a “lap seal” or a “fin seal” The tube then is pulledvertically downwards to a filling station and collapsed across itstransverse cross-section. The position of such cross-section is at asealing device below the filling station, which makes an air-tighttransverse heat seal at the collapsed portion of the tube.

Next, the flowable material to be packaged enters the tube above thetransverse heat seal, continuously or intermittently, filling the tubeupwardly from the transverse heat seal. The tube is then allowed to dropa predetermined distance usually under the influence of the weight ofthe material in the tube. Depending on the material being packaged andthe packaging process, the jaws of the sealing device are closed again.The tube collapses as a result at a second transverse section that isat, above, or below the air/material interface in the tube. The sealingdevice seals and severs the tube transversely at the second transversesection.

The material-filled portion of the tube is now in the form of a pillowshaped pouch. Thus, the sealing device has sealed the top of the filledpouch, sealed the bottom of the next-to-be-formed pouch and separatedthe filled pouch from the next-to-be-formed pouch, all in one operation.

One VFFS apparatus of the type described above is a Prepac® IS-7E liquidpackaging apparatus. A commonly used sealing device, the so-calledimpulse sealer, has electrically insulated sealing element mounted inthe sealing jaws. In operation, the sealing jaws close andsimultaneously an electrical current flows through the sealing element,for example, a wire. The jaws remain closed while the seal forms, butnot while it cools and solidifies. Therefore, once the sealing jawsopen, the synthetic thermoplastic film must provide a molten transverseseal that supports the weight of the flowable material, for example,liquid, in the next-to-be-formed pouch.

For reasons of economy, customers are demanding thinner and thinnerfilms for the pouching of fluids. This can lead to one of two problemsin commercially available film formulations: (1) inadequate sealabilityand toughness, or (2) insufficient stiffness.

Pouches made from commercially available films tend to suffer fromdefective seals, that is, a tendency to have weak transverse end and/orlongitudinal seals even though the operating conditions of the impulsesealer have been optimized. Defective seals may lead to the phenomenonknown as “leakers”, in which the flowable material, for example, milk,may escape from the pouch through pinholes that develop at, or close, tothe seal. It has been estimated that leakers account for about 1-2% ofthe 1.3 liter milk pouch production.

As the pouch film is down-gauged for reasons of economy, its stiffnessmay also become an issue. Lack of stiffness may adversely affect therunnability of the film on a form, fill and seal apparatus and give poorstand-up properties for pouches in, for instance, a milk pitcher.However, higher stiffness has traditionally required a thicker gauge ofthe pouch film. But thicker gauge requires more material. The presentinvention, by localizing the stiffening material towards the outside ofthe multi-layer film, addresses both these issues in that the stiffnessof the multi-layer film is not adversely affected even when its gaugethickness is reduced.

SUMMARY OF INVENTION

The present invention relates to a multi-layer film for making pouchesfor containing flowable materials, said multi-layer film comprising thefollowing layers in order, from an at least one inner sealant-layer toan at least one outer sealant-layer:

-   -   (A) said at least one inner sealant-layer comprising        polyethylene that is selected from the group consisting of:        -   (i) an at least one low-density ethylene-alpha-olefin            copolymer,        -   (ii) a blend of said at least one low-density            ethylene-alpha-olefin copolymer and an at least one ethylene            homopolymer, wherein said ethylene homopolymer is made in a            high-pressure polymerization process; and        -   (iii) a blend of said at least one low-density            ethylene-alpha-olefin copolymer and an at least one ethylene            copolymer, wherein said ethylene copolymer is made in a            high-pressure polymerization process;    -   (B) a first at least one interposed layer adjacent to said at        least one inner sealant-layer, said first at least one        interposed layer comprising:        -   (i) an at least one high-density polyethylene, or a blend of            said at least one high-density polyethylene and at least one            ethylene-alpha-olefin copolymer;        -   (ii) optionally, an ethylene homopolymer made in a            high-pressure polymerization process;        -   (iii) optionally, an ethylene copolymer made in a high            pressure polymerization process; and        -   (iv) optionally, a second ethylene-alpha-olefin copolymer            that is not the same as said at least one            ethylene-alpha-olefin copolymer in (B)(i);        -   wherein the centerline of said first at least one interposed            layer is closer to the centerline of said at least one inner            sealant-layer than to the centerline of said multi-layer            film;    -   (C) at least one core layer, adjacent to said first at least one        interposed layer, said at least one core layer comprising        polyethylene that is selected from the group consisting of:        -   (i) at least one low-density ethylene-alpha olefin            copolymer,        -   (ii) a blend of said at least one low-density            ethylene-alpha-olefin copolymer and an at least one ethylene            homopolymer, wherein said ethylene homopolymer is made in a            high-pressure polymerization process; and        -   (iii) a blend of said at least one low-density            ethylene-alpha-olefin copolymer and an at least one ethylene            copolymer, wherein said ethylene copolymer is made in a            high-pressure polymerization process;    -   (D) a second at least one interposed layer adjacent to said at        least one core layer, said second at least one interposed layer        comprising:        -   (i) an at least one high-density polyethylene, or a blend of            said at least one high-density polyethylene and at least one            ethylene-alpha-olefin copolymer;        -   (ii) optionally, an ethylene homopolymer made in a            high-pressure polymerization process;        -   (iii) optionally, an ethylene copolymer made in a high            pressure polymerization process; and        -   (iv) optionally, a second ethylene-alpha-olefin copolymer            that is not the same as said at least one            ethylene-alpha-olefin copolymer in (D)(i);        -   wherein the centerline of said second at least one            interposed layer is closer to the center-line of said at            least one outer sealant-layer than to the centerline of said            multi-layer film; and    -   (E) said at least one outer sealant-layer, comprising        polyethylene that is selected from the group consisting of:        -   (i) an at least one low-density ethylene-alpha-olefin            copolymer,        -   (ii) a blend of said at least one low-density            ethylene-alpha-olefin copolymer and an at least one ethylene            homopolymer, wherein said ethylene homopolymer is made in a            high-pressure polymerization process; and        -   (iii) a blend of said at least one low-density            ethylene-alpha-olefin copolymer and an at least one ethylene            copolymer, wherein said ethylene copolymer is made in a            high-pressure polymerization process;        -   wherein said multi-layer film thickness is in the range of            from about 35 microns to about 66 microns;        -   wherein a combined thickness of said first at least one            interposed layer and said second at least one interposed            layer is in the range of from about 10% to about 27% of the            total thickness of said multi-layer film;        -   wherein a combined thickness of said inner sealant-layer and            said outer sealant-layer is in the range of from about 10%            to about 27% of the total thickness of said multi-layer            film; and        -   wherein said at least one high-density polyethylene in said            first at least one interposed layer and said second at least            one interposed layer has a density of at least of about            0.950 g/cm³ and a melt-index of less than 1.05 dg/min.

This invention also relates to a process for making pouches filled witha flowable material, using a vertical form, fill and seal apparatus,wherein each pouch is made from a flat web of film by the followingsteps:

-   -   (I) forming a tubular film therefrom with a longitudinal seal        and subsequently flattening said tubular film at a first        position;    -   (II) transversely heat-sealing said tubular film at the        flattened position;    -   (III) filling said tubular film with a predetermined quantity of        flowable material above said first position;    -   (IV) flattening said tubular film above the predetermined        quantity of flowable material at a second position; and    -   (V) transversely heat sealing said tubular film at said second        position,

wherein said pouches are made from a flat web of film made from amulti-layer film, comprising the following layers in order of an atleast one inner sealant-layer to an at least one outer sealant-layer:

-   -   (A) said at least one inner sealant-layer comprising        polyethylene that is selected from the group consisting of:        -   (i) an at least one low-density ethylene-alpha-olefin            copolymer,        -   (ii) a blend of said at least one low-density            ethylene-alpha-olefin copolymer and an at least one ethylene            homopolymer, wherein said ethylene homopolymer is made in a            high-pressure polymerization process; and        -   (iii) a blend of said at least one low-density            ethylene-alpha-olefin copolymer and an at least one ethylene            copolymer, wherein said ethylene copolymer is made in a            high-pressure polymerization process;    -   (B) a first at least one interposed layer adjacent to said at        least one inner sealant-layer, said first at least one        interposed layer comprising:        -   (i) an at least one high-density polyethylene, or a blend of            said at least one high-density polyethylene and at least one            ethylene-alpha-olefin copolymer;        -   (ii) optionally, an ethylene homopolymer made in a            high-pressure polymerization process;        -   (iii) optionally, an ethylene copolymer made in a high            pressure polymerization process; and        -   (iv) optionally, a second ethylene-alpha-olefin copolymer            that is not the same as said at least one            ethylene-alpha-olefin copolymer in (B)(i);        -   wherein the centerline of said first at least one interposed            layer is closer to the centerline of said at least one inner            sealant-layer than to the centerline of said multi-layer            film;    -   (C) at least one core layer, adjacent to said first at least one        interposed layer, said at least one core layer comprising        polyethylene that is selected from the group consisting of:        -   (i) at least one low-density ethylene-alpha olefin            copolymer,        -   (ii) a blend of said at least one low-density            ethylene-alpha-olefin copolymer and an at least one ethylene            homopolymer, wherein said ethylene homopolymer is made in a            high-pressure polymerization process; and        -   (iii) a blend of said at least one low-density            ethylene-alpha-olefin copolymer and an at least one ethylene            copolymer, wherein said ethylene copolymer is made in a            high-pressure polymerization process;    -   (D) a second at least one interposed layer adjacent to said at        least one core layer, said second at least one interposed layer        comprising:        -   (i) an at least one high-density polyethylene, or a blend of            said at least one high-density polyethylene and at least one            ethylene-alpha-olefin copolymer;        -   (ii) optionally, an ethylene homopolymer made in a            high-pressure polymerization process;        -   (iii) optionally, an ethylene copolymer made in a high            pressure polymerization process; and        -   (iv) optionally, a second ethylene-alpha-olefin copolymer            that is not the same as said at least one            ethylene-alpha-olefin copolymer in (D)(i);        -   wherein the centerline of said second at least one            interposed layer is closer to the center-line of said at            least one outer sealant-layer than to the centerline of said            multi-layer film; and    -   (E) said at least one outer sealant-layer, comprising        polyethylene that is selected from the group consisting of:        -   (i) an at least one low-density ethylene-alpha-olefin            copolymer,        -   (ii) a blend of said at least one low-density            ethylene-alpha-olefin copolymer and an at least one ethylene            homopolymer, wherein said ethylene homopolymer is made in a            high-pressure polymerization process; and        -   (iii) a blend of said at least one low-density            ethylene-alpha-olefin copolymer and an at least one ethylene            copolymer, wherein said ethylene copolymer is made in a            high-pressure polymerization process;        -   wherein said multi-layer film thickness is in the range of            from about 35 microns to about 66 microns;        -   wherein a combined thickness of said first at least one            interposed layer and said second at least one interposed            layer is in the range of from about 10% to about 27% of the            total thickness of said multi-layer film;        -   wherein a combined thickness of said inner sealant-layer and            said outer sealant-layer is in the range of from about 10%            to about 27% of the total thickness of said multi-layer            film; and        -   wherein said at least one high-density polyethylene in said            first at least one interposed layer and said second at least            one interposed layer has a density of at least of about            0.950 g/cm³ and a melt-index of less than 1.05 dg/min.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a general schematic of the multi-layer film of the presentinvention.

FIG. 2 shows the schematic of interposed layer having multiple layerswith varying concentrations of the HDPE polymer.

FIG. 3 shows a typical DSC melting curve for a heterogeneous LLDPEpolymer polymerized using a traditional Zeigler-Natta catalyst.

FIG. 4 shows a typical DSC melting curve for a homogeneous LLDPE polymerpolymerized using a single site catalyst.

DESCRIPTION OF THE INVENTION

Definitions

All percentages expressed in the present patent application are byweight of the total weight of the composition unless expressedotherwise.

All ratios expressed in this patent application are on a weight:weightbasis unless expressed otherwise.

In this patent application, ranges are used as shorthand only to avoidlisting and describing each and every value within the range. Anyappropriate value within the range can be selected as the upper value,the lower value, or the end-point of the range.

In this patent application, the singular form of a word includes itsplural, and vice versa, unless the context clearly dictates otherwise.Thus, references “a,” “an,” and “the” generally include the plurals ofthe respective terms they qualify. For example, reference to “a method”includes its plural—“methods.” Similarly, the terms “comprise,”“comprises,” and “comprising,” whether used as a transitional phrase inthe claims or otherwise, should be interpreted inclusively rather thanexclusively. Likewise the terms “include,” “including,” and “or” shouldbe construed to be inclusive, unless such a construction is clearlyprohibited from the context. Similarly, the term “examples,”particularly when followed by a listing of terms, is merely exemplaryand illustrative and should not be deemed to be exclusive orcomprehensive.

The methods, compositions, and other advances disclosed in this patentapplication are not limited to particular methodology, protocols, andreagents described in the application because, as the skilled artisanwill appreciate, they may vary. Further, the terminology used in thisapplication describes particular embodiments only, and should not beconstrued as limiting the scope of what is disclosed or claimed.

Unless defined otherwise, all technical and scientific terms, terms ofart, and acronyms used in the present application have the meaningscommonly understood by one of ordinary skill in the art in the field(s)of the invention, or in the field(s) where the term is used. Althoughany compositions, methods, articles of manufacture, or other means ormaterials similar or equivalent to those described in the present patentapplication can be used in the practice of the present invention,specific compositions, methods, articles of manufacture, or other meansor materials are described only for exemplification.

All patents, patent applications, publications, technical and/orscholarly articles, and other references cited or referred to in thispatent application are incorporated in their entirety by reference tothe extent allowed by law. The discussion of those references isintended merely to summarize the assertions made in these references. Noadmission is made that any such patents, patent applications,publications or references, or any portion thereof, are relevant,material, or prior art. The right to challenge the accuracy andpertinence of any assertion of such patents, patent applications,publications, and other references as relevant, material, or prior artis specifically reserved.

General Invention

As used herein, the term “flowable material” does not include gaseousmaterials, but encompasses materials which are flowable under gravity ormay be pumped. Such materials include liquids, for example, milk, water,fruit juice, oil; emulsions, for example, ice cream mix, soft margarine;pastes, for example, meat pastes, peanut butter; preserves, for example,jams, pie fillings, marmalade; jellies; doughs; ground meat, forexample, sausage meat; powders, for example, gelatin powders,detergents; granular solids, for example, nuts, sugar; and likematerials. The invention described herein is particularly useful forflowable foods such as milk In addition, as used herein “density” isdetermined by ASTM Procedure D1505-85, “stiffness” is understood to betensile modulus of elasticity as measured by ASTM Procedure D882-91(Method A) and “melt-index” by ASTM Procedure D1238-90B (Condition E).The “melting point” of a polymer is measured as the peak melting pointwhen performing differential scanning calorimetry (DSC) as described inASTM Procedure D3417-83 (rev. 88).

In one embodiment, this invention relates to polyethylene-basedmulti-layer films usable for pouch-making for containing of flowablematerials. More specifically, this invention provides a multi-layer filmthat is lower in gauge (thickness) but retains an adequate combinationof stiffness and toughness for its use in pouches for flowablematerials.

In one embodiment, the polyethylene-based multi-layer film comprisesfive layers (FIG. 1): an inner sealant-layer (1), a first interposedlayer (2), a core layer (3), a second interposed layer (4), and theouter sealant-layer (5). The interposed layer comprises a stiffpolymer—high density polyethylene (HDPE). Moreover, a combined thicknessof the first and the second interposed layer is in the range of fromabout 10% to about 27% of the total thickness of the multi-layer film.Similarly, a combined thickness of the inner and outer sealant-layers isalso in the range of from about 10% to about 27% of the total thicknessof the multi-layer film. Stated another way, the core layer thicknessranges from about 46% (See FIG. 1A) to about 80% (see FIG. 1B) of thetotal thickness of the multi-layer film. Because generally, the HDPE islocalized in the interposed layer and not distributed across themulti-layer film of the present invention, and because of the rangelimitations on the sealant layers and the interposed layers, the HDPEresides much closer to the center-line of the inner and the outersealant-layers than to the centerline of the multi-layer film. As aresult, the multi-layer film of the present invention provides alowering of the gauge at a performance substantially similar to thosefilms that are higher in their gauge. A HDPE film cannot be used on itsown for fluid packaging because, for example, it lacks the requiredsealing properties. Moreover, if the HDPE is distributed throughout thepouch-making film, it renders the film hazy and unclear. However, clearfilm is desired, for example, for making milk pouches. The presentinvention thus addresses all these issues.

This invention also relates to a process for making such multi-layerfilms and to pouches made from such multi-layer films.

More specifically, in one embodiment, the present invention relates to apolyethylene-based multi-layer film that is from about 35 microns toabout 66 microns thick, for making pouches for containing flowablematerials. The multi-layer film comprises the following layers: an atleast one inner sealant-layer, a first at least one interposed layer, anat least one core layer, a second at least one interposed layer, and anat least one outer sealant-layer, in order, from an at least one innersealant-layer to an at least one outer sealant-layer; wherein:

-   -   (A) said at least one inner sealant-layer and/or said at least        one outer sealant-layer comprises polyethylene that is selected        from the group consisting of:        -   (i) an at least one low-density ethylene-alpha-olefin            copolymer,        -   (ii) a blend of said at least one low-density            ethylene-alpha-olefin copolymer and an at least one ethylene            homopolymer, wherein said ethylene homopolymer is made in a            high-pressure polymerization process; and        -   (iii) a blend of said at least one low-density            ethylene-alpha-olefin copolymer and an at least one ethylene            copolymer, wherein said ethylene copolymer is made in a            high-pressure polymerization process;        -   wherein a combined thickness of said inner sealant-layer and            said outer sealant-layer is in the range of from about 10%            to about 27% of the total thickness of said multi-layer            film;    -   (B) the first and/or the second at least one interposed layer is        adjacent to said at least one inner sealant-layer or outer        sealant-layer, respectively, and said first and/or the second at        least one interposed layer comprises:        -   (i) an at least one high-density polyethylene, or a blend of            said at least one high-density polyethylene and at least one            ethylene-alpha-olefin copolymer;        -   (ii) optionally, an ethylene homopolymer made in a            high-pressure polymerization process;        -   (iii) optionally, an ethylene copolymer made in a high            pressure polymerization process; and        -   (iv) optionally, a second ethylene-alpha-olefin copolymer            that is not the same as said at least one            ethylene-alpha-olefin copolymer in (B)(i);        -   wherein the centerline of said first and/or the second at            least one interposed layer is closer to the centerline of            said at least one inner sealant-layer or at least one outer            sealant layer, respectively, than to the centerline of said            multi-layer film;        -   wherein a combined thickness of said first at least one            interposed layer and said second at least one interposed            layer is in the range of from about 10% to about 27% of the            total thickness of said multi-layer film; and        -   wherein said at least one high-density polyethylene in said            first at least one interposed layer and/or said second at            least one interposed layer has a density of at least of            about 0.950 g/cm³ and a melt-index of less than 1.05 dg/min;            and    -   (C) said at least one core layer, adjacent to said first at        least one interposed layer, comprises polyethylene that is        selected from the group consisting of:        -   (i) at least one low-density ethylene-alpha olefin            copolymer,        -   (ii) a blend of said at least one low-density            ethylene-alpha-olefin copolymer and an at least one ethylene            homopolymer, wherein said ethylene homopolymer is made in a            high-pressure polymerization process; and        -   (iii) a blend of said at least one low-density            ethylene-alpha-olefin copolymer and an at least one ethylene            copolymer, wherein said ethylene copolymer is made in a            high-pressure polymerization process.

In a preferred embodiment, the multi-layer film thickness is in therange of from about 38 microns to about 63 microns. In a furtherpreferred embodiment, the multi-layer film thickness is in the range offrom about 44 microns to about 60 microns. In another preferredembodiment, the multi-layer film thickness is in the range of from about47 microns to about 59 microns. In yet another embodiment, themulti-layer film thickness is selected from the group consisting ofabout 33 microns, about 34 microns, about 35 microns, about 36 microns,about 37 microns, about 38 microns, about 39 microns, about 40 microns,about 41 microns, about 42 microns, about 43 microns, about 44 microns,about 45 microns, about 46 microns, about 47 microns, about 48 microns,about 49 microns, about 50 microns, about 51 microns, about 52 microns,about 53 microns, about 54 microns, about 55 microns, about 56 microns,about 57 microns, about 58 microns, about 59 microns, about 60 microns,about 61 microns, about 62 microns, about 63 microns, about 64 microns,and about 66 microns. In a further preferred embodiment, said combinedfilm thickness can be a number (integer or non-integer) between any twointeger numbers between and including 33 microns and 66 micronsidentified supra. For example, the combined thickness can be about 33.1microns, about 33.2 microns, about 33.3 microns, about 33.4 microns,about 33.5 microns, about 33.6 microns, about 33.7 microns, about 33.8microns, about 33.9 microns, and so on and so forth.

In a preferred embodiment, the combined thickness of said first at leastone interposed layer and said second at least one interposed layer is inthe range of from about 10% to about 27% of the total thickness of saidmulti-layer film. In a preferred embodiment, the multi-layer filmthickness is selected from the group consisting of about 10%, about 11%,about 12%, about 13%, about 14%, about 15%, about 16%, about 17% s,about 18%, about 19%, about 20%, about 21% s, about 22%, about 23%,about 24%, about 25%, about 26%, and about 27%. In a preferredembodiment, said combined film thickness can be a number (integer ornon-integer) between any two integer numbers between and including 10%and 27% identified supra. For example, the combined thickness can beabout 10.1%, about 10.2%, about 10.3%, about 10.4%, about 10.5%, about10.6%, about 10.7%, about 10.8%, about 10.9%, and so on and so forth.

Similarly, in a preferred embodiment, the combined thickness of saidinner and said outer sealant layers is in the range of from about 10% toabout 27% of the total thickness of said multi-layer film. In apreferred embodiment, the multi-layer film thickness is selected fromthe group consisting of about 10%, about 11%, about 12%, about 13%,about 14%, about 15%, about 16%, about 17%, about 18%, about 19%, about20%, about 21%s, about 22%, about 23%, about 24%, about 25%, about 26%,and about 27%. In a preferred embodiment, said combined film thicknesscan be a number (integer or non-integer) between any two integer numbersbetween and including 10% and 27% identified supra. For example, thecombined thickness can be about 10.1%, about 10.2%, about 10.3%, about10.4%, about 10.5%, about 10.6%, about 10.7%, about 10.8%, about 10.9%,and so on and so forth.

In yet another embodiment of the invention, the density of the HDPE inthe interposed layer is selected from about 0.950, about 0.951 g/cm³,about 0.952 g/cm³, about 0.953 g/cm³, about 0.954 g/cm³, about 0.955g/cm³, about 0.956 g/cm³, about 0.957 g/cm³, about 0.958 g/cm³, about0.959 g/cm³, about 0.960 g/cm³, about 0.961 g/cm³, about 0.962 g/cm³,about 0.963 g/cm³, about 0.964 g/cm³, about 0.965 g/cm³, about 0.966g/cm³, about 0.967 g/cm³, about 0.968 g/cm³, and about 0.969 g/cm³.

In yet another embodiment of the invention, the melt-index of the HDPEin the interposed layer, as measured in dg/min, is selected from about1.04, about 1.03, about 1.02, about 1.01, about 1.00, about 0.99, about0.98, about 0.97, about 0.96, about 0.95, about 0.94, about 0.93, and soon and so forth down to about 0.30.

The Inner and the Outer Sealant-Layer

In one embodiment, the multi-layer film comprises an at least one innersealant layer, and an at least one outer sealant layer. The innersealant layer is externally on one side of the multi-layer film, and theouter sealant layer is externally on the other side of the multi-layerfilm

The multi-layer film comprises one inner sealant layer or more than oneinner sealant-layers. For example, the multi-layer film can have two,three, or four inner sealant-layers stacked adjacent to each other.Similarly, the multi-layer film comprises one outer sealant layer ormore than one outer sealant layers. For example, the multi-layer filmcan have two, three, or four outer sealant layers.

While it may be preferred that the inner sealant-layer and the outersealant layer thicknesses are approximately the same, in other preferredembodiments, their thicknesses may not be the same.

Also, while it is preferred that the multi-layer film of the presentinvention comprises the same number of inner sealant-layers and theouter sealant layers, in other embodiments, the number of inner sealantlayers may be different from the number of outer sealant layers.

For this invention, the total combined thickness of said at least oneinner sealant layer and said at least one outer sealant layer is fromabout 10% to about 27% of the total thickness of the multi-layer film.In other embodiments of the invention, the total combined thickness ofthe sealant layers can be about 11%, about 12%, about 13%, about 14%,about 15%, about 16%, about 17%, about 18%, about 19%, about 20%, about21%, about 22%, about 23%, about 24%, about 25%, about 26%, and about27% of the total thickness of the multi-layer film. The total combinedthickness of the sealant layers can also be intermediate percentagebetween the percentages cited supra—for example, a total combinedthickness that is from about 11.1%, about 11.2%, about 11.3%, about11.4%, and so on and so forth between other percentages cited.

The at least one inner sealant-layer and the at least one outersealant-layer comprise polyethylene that is selected from the groupconsisting of:

-   -   (i) an at least one low-density ethylene-alpha-olefin copolymer,    -   (ii) a blend of said at least one low-density        ethylene-alpha-olefin copolymer and an at least one ethylene        homopolymer, wherein said ethylene homopolymer is made in a        high-pressure polymerization process; and    -   (iii) a blend of said at least one low-density        ethylene-alpha-olefin copolymer and an at least one ethylene        copolymer, wherein said ethylene copolymer is made in a        high-pressure polymerization process.

The ethylene homopolymer used in the at least one inner sealant layer orin the at least one outer sealant layer, in one embodiment, is made in ahigh-pressure polymerization process. One or more ethylene homopolymerscan be used in the at least one inner sealant layer or in the at leastone outer sealant layer. In one embodiment, the weight percent of theethylene homopolymer is from 0 to about 15 parts by weight of said atleast one inner sealant layer or said at least one outer sealant layer.In other embodiments, the weight percent range of the ethylenehomopolymer can be defined by any two numbers from about 0.0, about 0.5,about 1.0, about 1.5, about 2.0, about 2.5, about 3.0, about 3.5, about4.0, about 4.5, about 5.0, about 5.5, about 6.0, about 6.5, about 7.0,about 7.5, about 8.0, about 8.5, about 9.0, about 9.5, about 10.0, about10.5, about 11.0, about 11.5, about 12.0, about 12.5, about 13.0, about13.5, about 14.0, about 14.5, and about 15.0 parts by weight of said atleast one inner sealant layer or said at least one outer sealant layer.The ethylene homopolymer has a density in the range of from about 0.918to about 0.923 g/cm³, and a melt-index in the range of from about 0.1 toabout 1.1 dg/min. In other embodiments, the ethylene homopolymer densityrange can be defined by any two numbers, namely, about 0.918, about0.919, about 0.920, about 0.921, about 0.922, and about 0.923 g/cm³.Similarly, the melt-index range can also be defined by any two numbers,namely, about 0.1, about 0.2, about 0.3, about 0.4, about 0.5, about0.6, about 0.7, about 0.8, about 0.9, about 1.0, and 1.1 dg/min.

In another embodiment, more than one ethylene homopolymers may be usedin one or more layers of the inner sealant layer or the outer sealantlayers. The number of ethylene homopolymers and the type of ethylenehomopolymers may vary between any two inner sealant layers or the outersealant layers. For example, a multi-layer film comprises three innersealant-layers (I₁, I₂, and I₃) and three outer sealant layers (O₁, O₂,and O₃). In one embodiment, I₁, I₂, and I₃, and O₁, O₂, and O₃, forexample, may have only one and the same ethylene homopolymer. In anotherembodiment, I₁, I₂, and I₃ may have the same ethylene homopolymer, butdifferent from O₁, O₂, and O₃. In another embodiment, for example, I₁may have two ethylene homopolymers while I₂ may have three ethylenehomopolymers, while I₃ may have no ethylene homopolymer. Two ethylenehomopolymers may differ from each other by having different densities,different melt-indices, different molecular weights, or different branchstructures.

The ethylene copolymer used in the at least one inner sealant layer orin the at least one outer sealant layer, in one embodiment, is made in ahigh-pressure polymerization process. One or more ethylene copolymerscan be used in the at least one inner sealant layer or in the at leastone outer sealant layer. In one embodiment, the weight percent of theethylene homopolymer is from 0 to about 15 parts by weight of said atleast one inner sealant layer or said at least one outer sealant layer.In other embodiments, the weight percent range of the ethylenehomopolymer can be defined by any two numbers from about 0.0, about 0.5,about 1.0, about 1.5, about 2.0, about 2.5, about 3.0, about 3.5, about4.0, about 4.5, about 5.0, about 5.5, about 6.0, about 6.5, about_(7.0,) about 7.5, about 8.0, about 8.5, about 9.0, about 9.5, about10.0, about 10.5, about 11.0, about 11.5, about 12.0, about 12.5, about13.0, about 13.5, about 14.0, about 14.5, and about 15.0 parts byweight. The ethylene copolymer has a density in the range of from about0.930 to about 0.960 g/cm³, and a melt-index in the range of from about0.1 to about 10 dg/min. The density range can also be defined by any twonumbers from about 0.930, about 0.931, . . . , about 0.958, about 0.959,and about 0.960 g/cm³.

In another embodiment, more than one ethylene copolymers may be used inone or more layers of the inner sealant layer or the outer sealantlayers. The number of ethylene copolymers and the type of ethylenecopolymers may vary between any two inner sealant layers or the outersealant layers. For example, a multi-layer film comprises three innersealant-layers (I₁, I₂, and I₃) and three outer sealant layers (O₁, O₂,and O₃). In one embodiment, I₁, I₂, and I₃, and O₁, O₂, and O₃, forexample, may have only one and the same ethylene copolymer. In anotherembodiment, I₁, I₂, and I₃ may have the same ethylene copolymer, butdifferent from O₁, O₂, and O₃. In another embodiment, for example, Itmay have two ethylene copolymers while I₂ may have three ethylenecopolymers, while I₃ may have no ethylene copolymer. Two ethylenecopolymers may differ from each other by having different densities,different melt-indices, different molecular weights, or different branchstructures.

The comonomer of ethylene in the ethylene copolymer described in theforegoing can be chosen from polar monomers such as vinyl acetate,acrylic acid, methacrylic acid, and vinyl methacrylate, wherein theethylene copolymer is manufactured in a high-pressure polymerizationprocess. The concentration of polar comonomer must be kept relativelylow in order that the copolymer has good compatibility with the majorpolyethylene component of the sealant layer(s). For example, ethylenevinyl acetate copolymers should contain less than or equal to 15 wt %vinyl acetate. Otherwise, poor optical appearance, and even poorintra-layer adhesion, can result.

In another embodiment, the at least one inner sealant layer or the atleast one outer sealant layer comprises at least one low-densityethylene-alpha-olefin copolymer, which may be found alone or in a blendform with an ethylene homopolymer described supra, or ethylene copolymerdescribed supra. Such low-density ethylene alpha-olefin copolymer, in apreferred embodiment, is found as a copolymer that is from about 80 toabout 98 parts by weight of the at least one inner or the at least oneouter sealant layer weight. The copolymer range can also be defined byany two numbers from about 80, about 81, about 82, . . . , about 96,about 97, and about 98 parts by weight of the at least one inner or theat least one outer sealant layer weight. The copolymer is a low-densitycopolymer of ethylene and an at least one. C₄-C₁₀ alpha-olefinmanufactured in a polymerization process using a single-sitepolymerization catalyst, with a density in the range of from about 0.909to about 0.935 g/cm³ and a melt-index in the range of from about 0.5 toabout 1.5 dg/min. The density range can also be defined by any twonumbers from about 0.909, about 0.910, about 0.911, . . . , about 0.933,about 0.934, and about 0.935 g/cm³. Similarly, the melt-index range canbe defined by any two numbers from about 0.5, about 0.6, about 0.7,about 0.8, about 0.9, about 1.0, and about 1.1 dg/min. In addition, saidembodiment further comprises, from about 0 to about 15 parts by weightof an additional at least one low-density copolymer of ethylene and anat least one C₄-C₁₀ alpha-olefin. In other embodiments, the weightpercent range of the ethylene homopolymer can be defined by any twonumbers from about 0.0, about 0.5, about 1.0, about 1.5, about 2.0,about 2.5, about 3.0, about 3.5, about 4.0, about 4.5, about 5.0, about5.5, about 6.0, about 6.5, about 7.0, about 7.5, about 8.0, about 8.5,about 9.0, about 9.5, about 10.0, about 10.5, about 11.0, about 11.5,about 12.0, about 12.5, about 13.0, about 13.5, about 14.0, about 14.5,and about 15.0 parts by weight. Said additional at least one low-densitycopolymer is an ultra-low density copolymer of ethylene and said atleast one C₄-C₁₀ alpha-olefin, manufactured in a polymerization processusing a single-site polymerization catalyst, with a density in the rangeof from about 0.859 to about 0.888 g/cm³ and a melt-index in the rangeof from about 0.4 to about 0.6 dg/min. The density range can also bedefined by any two numbers from about 0.859, about 0.860, about 0.861, .. . , about 0.886, about 0.887, and about 0.888 g/cm³. Similarly, themelt-index range can be defined by any two numbers from about 0.4, about0.45, about 0.5, about 0.55, and about 0.6 dg/min.

In another embodiment, the foregoing low-density copolymer of ethyleneand at least one C₄-C₁₀ alpha-olefin, or said at least one ultra-lowdensity copolymer of ethylene and at least one C₄-C₁₀ alpha-olefin isselected from ethylene/butene-1 copolymers, ethylene/hexene-1copolymers, ethylene/octene-1 copolymers, ethylene/octene-1/butene-1terpolymers and ethylene/hexene-1/butene-1 terpolymers.

The C₄-C10 alpha-olefin also includes the cyclic counterparts.

In a preferred embodiment, the thickness of said at least one sealantlayer is from about 2 microns about 20 microns. The thickness of said atleast one sealant layer can be about 3, about 4, about 5, about 6, about7, about 8, about 9, about 10, about 11, about 12, about 13, about 14,about 15, about 16, about 17, about 18, about 19, or about 20 microns.

The First and the Second Interposed Layer

In one embodiment, the multi-layer film comprises a first at least oneinterposed layer adjacent to an at least one inner sealant layer and toan at least one core layer on the other side, and a second at least oneinterposed layer adjacent to said core layer on the other side of thesaid first at least one interposed layer and adjacent to an at least oneouter sealant layer. The inner sealant layer is externally on one sideof the multi-layer film, and the outer sealant layer is externally onthe other side of the multi-layer film.

The multi-layer film comprises one first interposed layer or more thanone first interposed layers. For example, the multi-layer film can havetwo, three, or four first interposed layers stacked adjacent to eachother. Similarly, the multi-layer film comprises one second interposedlayer or more than one second interposed layers. For example, themulti-layer film can have two, three, or four second interposed layers.

While it may be preferred that the first interposed layer and the secondinterposed layer thicknesses are approximately the same, in otherpreferred embodiments, their thicknesses may not be the same.

Also, while it is preferred that the multi-layer film of the presentinvention comprises the same number of first interposed layers and thesecond interposed layers, in other embodiments, the number of firstinterposed layers may be different from the number of second interposedlayers.

In this invention, the centerline of said first at least one interposedlayer is closer to the centerline of said at least one innersealant-layer than to the centerline of said multi-layer film. If morethan one first interposed layers are present, then reference is made tothe centerline of the combined set of first interposed layers.Similarly, if there is more than one inner sealant layer, then referenceis made to the centerline of the combined set of inner sealant layers.

For this invention, the total combined thickness of said first at leastone interposed layer and said second at least one interposed layer isfrom about 10% to about 27% of the total thickness of the multi-layerfilm. In other embodiments of the invention, the total combinedthickness of said first at least one interposed layer and said second atleast one interposed layer can be about 11%, about 12%, about 13%, about14%, about 15%, about 16%, about 17%, about 18%, about 19%, about 20%,about 21%, about 22%, about 23%, about 24%, about 25%, about 26%, andabout 27% of the total thickness of the multi-layer film. The totalcombined thickness of the interposed layers can also be intermediatepercentage between the percentages cited supra—for example, a totalcombined thickness that is from about 11.1%, about 11.2%, about 11.3%,about 11.4%, and so on and so forth between other percentages cited.

The first at least one interposed layer and the second at least oneinterposed layer comprise:

-   -   (i) an at least one high-density polyethylene, or a blend of        said at least one high-density polyethylene and at least one        ethylene-alpha-olefin copolymer;    -   (ii) optionally, an ethylene homopolymer made in a high-pressure        polymerization process;    -   (iii) optionally, an ethylene copolymer made in a high pressure        polymerization process; and    -   (iv) optionally, a second ethylene-alpha-olefin copolymer that        is not the same as said at least one ethylene-alpha-olefin        copolymer in (i).

The at least one high-density polyethylene (HDPE) is in the range offrom about 78 to about 100 parts by weight of said first at least oneinterposed layer or of said second at least one interposed layer. Therange can also be defined by any two numbers from about 78, about 79,about 80, . . . , about 98, about 99, and about 100 parts. The at leastone HDPE is manufactured in a polymerization process using a single-sitepolymerization catalyst or a Ziegler-Natta catalyst. The at least oneHDPE has a density greater than 0.950 g/cm³ and a melt-index in therange of from about 0.75 to about 1.05 dg/min. The melt-index range canbe defined by any two numbers from about 0.75, about 0.80, about 0.85,about 0.90, about 0.95, about 1.00, and about 1.05 dg/min.

In another embodiment, the first or the second at least one interposedlayers comprises a first at least one ethylene-alpha olefin copolymer.The ethylene-alpha olefin copolymer is in the range of from about 0 toabout 15 parts by weight of said first at least one interposed layer orof said second at least one interposed layer. In other embodiments, theweight percent range of the—alpha olefin copolymer can be defined by anytwo numbers from about 0.0, about 0.5, about 1.0, about 1.5, about 2.0,about 2.5, about 3.0, about 3.5, about 4.0, about 4.5, about 5.0, about5.5, about 6.0, about 6.5, about 7.0, about 7.5, about 8.0, about 8.5,about 9.0, about 9.5, about 10.0, about 10.5, about 11.0, about 11.5,about 12.0, about 12.5, about 13.0, about 13.5, about 14.0, about 14.5,and about 15.0 parts by weight. The copolymer is an ultra-low-densitycopolymer of ethylene and an at least one C₄-C10 alpha-olefinmanufactured in a polymerization process using a single-sitepolymerization catalyst, with a density in the range of from about 0.859to about 0.905 g/cm³ and a melt-index in the range of from about 0.4 toabout 1.1 dg/min. The density range can also be defined by any twonumbers from about 0.859, about 0.860, about 0.861, . . . , about 0.903,about 0.904, and about 0.905 g/cm³. Similarly, the melt-index range canalso be defined by any two numbers from about 0.4, about 0.5, about 0.6,about 0.7, about 0.8, about 0.9, about 1.0, and 1.1 dg/min.

In yet another embodiment, said at least one optional ethylenehomopolymer is manufactured in a high pressure polymerization process,and is in the range of from about 0 parts to 15 parts by weight of saidfirst at least one interposed layer or of said second at least oninterposed layer. In other embodiments, the weight percent range of atleast one optional ethylene homopolymer can be defined by any twonumbers from about 0.0, about 0.5, about 1.0, about 1.5, about 2.0,about 2.5, about 3.0, about 3.5, about 4.0, about 4.5, about 5.0, about5.5, about 6.0, about 6.5, about 7.0, about 7.5, about 8.0, about 8.5,about 9.0, about 9.5, about 10.0, about 10.5, about 11.0, about 11.5,about 12.0, about 12.5, about 13.0, about 13.5, about 14.0, about 14.5,and about 15.0 parts by weight. The ethylene homopolymer has a densityin the range of from about 0.918 to about 0.923 g/cm³ and a melt-indexin the range of from about 0.1 to 1.1 dg/min. In other embodiments, theethylene homopolymer density range can be defined by any two numbers,namely, about 0.918, about 0.919, about 0.920, about 0.921, about 0.922,and about 0.923 g/cm³, Similarly, the melt-index range can also bedefined by any two numbers, namely, about 0.1, about 0.2, about 0.3,about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, about 0.9, about1.0, and 1.1 dg/min.

In yet another embodiment, said at least one optional ethylene copolymeris manufactured in a high pressure polymerization process, and is in therange of from about 0 parts to 15 parts by weight of said first at leastone interposed layer or of said second at least on interposed layer. Inother embodiments, the weight percent range of said at least oneoptional ethylene copolymer can be defined by any two numbers from about0.0, about 0.5, about 1.0, about 1.5, about 2.0, about 2.5, about 3.0,about 3.5, about 4.0, about 4.5, about 5.0, about 5.5, about 6.0, about6.5, about 7.0, about 7.5, about 8.0, about 8.5, about 9.0, about 9.5,about 10.0, about 10.5, about 11.0, about 11.5, about 12.0, about 12.5,about 13.0, about 13.5, about 14.0, about 14.5, and about 15.0 parts byweight of said first at least one interposed layer or of said second atleast on interposed layer. The ethylene copolymer has a density in therange 0.930 to about 0.960 g/cm³ and a melt-index in the range of fromabout 0.1 to about 10 dg/min. In other embodiments, the ethylenecopolymer density range can be defined by any two numbers from about0.930, about 0.931, about 0.932, . . . , about 0.958, about 0.959, andabout 0.960 g/cm³.

In another embodiment, the second ethylene-alpha-olefin copolymer is inthe range of from about 0 parts to 15 parts by weight, and can bemanufactured in a polymerization process using either a single-site orZeigler-Natta polymerization catalyst, wherein said copolymer has adensity in the range of from about 0.909 to about 0.935 g/cm³ and amelt-index in the range of from about 0.5 to about 1.5 dg/min. In otherembodiments, the weight percent range of said secondethylene-alpha-olefin copolymer can be defined by any two numbers fromabout 0.0, about 0.5, about 1.0, about 1.5, about 2.0, about 2.5, about3.o, about 3.5, about 4.0, about 4.5, about 5.0, about 5.5, about 6.0,about 6.5, about 7.0, about 7.5, about 8.0, about 8.5, about 9.0, about9.5, about 10.0, about 10.5, about 11.0, about 11.5, about 12.0, about12.5, about 13.0, about 13.5, about 14.0, about 14.5, and about 15.0parts by weight. The density range can also be defined by any twonumbers from about 0.909, about 0.910, about 0.911, . . . , about 0.933,about 0.934, and about 0.935 g/cm³. Similarly, the melt-index range canbe defined by any two numbers from about 0.5, about 0.6, about 0.7, . .. , about 1.3, about 1.4, and about 1.5 dg/min. The secondethylene-alpha-olefin copolymer is not the same as the first at leastone ethylene-alpha olefin copolymer described supra.

In another embodiment, more than one ethylene homopolymers may be usedin one or more layers of the first at least one interposed layer or inthe second at least one interposed layer. The number of ethylenehomopolymers and the type of ethylene homopolymers may vary between anytwo first interposed layers or any two second interposed layers. Forexample, a multi-layer film comprises three first interposed layers (F₁,F₂, and F₃) and three second interposed layers (S₁, S₂, and S₃). In oneembodiment, F_(l, F)2, and F3, and S₁, S₂, and S₃, for example, may haveonly one and the same ethylene homopolymer. In another embodiment, F₁,F₂, and F₃ may have the same ethylene homopolymer, but different fromS₁, S₂, and S₃. In another embodiment, for example, F₁ may have twoethylene homopolymers while F₂ may have three ethylene homopolymers,while F₃ may have no ethylene homopolymer. Two ethylene homopolymers maydiffer from each other by having different densities, differentmelt-indices, different molecular weights, or different branchstructures.

In another embodiment, more than one ethylene copolymers may be used inone or more layers of the first interposed layer or the secondinterposed layer. The number of ethylene copolymers and the type ofethylene copolymers may vary between any two first interposed layers orany two second interposed layers. For example, a multi-layer filmcomprises three first interposed layers (F₁, F₂, and F₃) and threesecond interposed layers (S₁, S₂, and S₃). In one embodiment, F₁, F₂,and F₃, and S₁, S₂, and S₃, for example, may have only one and the sameethylene copolymer. In another embodiment, F₁, F₂, and F₃ may have thesame ethylene copolymer, but different from S₁, S₂, and S₃. In anotherembodiment, for example, F₁ may have two ethylene copolymers while F₂may have three ethylene copolymers, while F₃ may have no ethylenecopolymer. Two ethylene copolymers may differ from each other by havingdifferent densities, different melt-indices, different molecularweights, or different branch structures.

The comonomer of ethylene in the ethylene copolymer described in theforegoing can be chosen from polar monomers such as vinyl acetate,acrylic acid, methacrylic acid, and vinyl methacrylate, wherein theethylene copolymer is manufactured in a high-pressure polymerizationprocess. The concentration of polar comonomer must be kept relativelylow in order that the copolymer has good compatibility with the majorpolyethylene component of the sealant layer(s). For example, ethylenevinyl acetate copolymers should contain less than or equal to 15 wt %vinyl acetate. Otherwise, poor optical appearance, and even poorintra-layer adhesion, can result.

In another embodiment, the first or the second at least one interposedlayers comprises at least one high-density polyethylene, which may befound alone or in a blend form with an ethylene homopolymer describedsupra, or ethylene copolymer described supra. The at least onehigh-density polyethylene (HDPE) is in the range of from about 78 toabout 100 parts by weight of said first at least one interposed layer orof said second at least one interposed layer. The HDPE range can also bedefined by any two numbers from about 78, about 79, about 80, . . .about 98, about 99, and about 100 parts by weight of said first at leastone interposed layer or of said second at least one interposed layer.The at least one HDPE is manufactured in a polymerization process usinga single-site polymerization catalyst or a Ziegler-Natta catalyst. Theat least one HDPE has a density greater than 0.950 g/cm³ but less than0.970 g/cc, and a melt-index in the range of from about 0.75 to about1.05 dg/min. In other embodiments, the melt-index range can be definedby any two numbers from about 0.75, about 0.80, about 0.85, about 0.90,about 0.95, about 0.100, and about 1.05 dg/min.

In addition, said embodiment can further comprise, from about 0 to about15 parts by weight of an at least one low-density copolymer of ethyleneand an at least one C₄-C₁₀ alpha-olefin. In other embodiments, theweight percent range of an at least one low-density copolymer ofethylene and an at least one C₄-C₁₀ alpha-olefin can be defined by anytwo numbers from about 0.0, about 0.5, about 1.0, about 1.5, about 2.0,about 2.5, about 3.0, about 3.5, about 4.0, about 4.5, about 5.0, about5.5, about 6.0, about 6.5, about 7.0, about 7.5, about 8.0, about 8.5,about 9.0, about 9.5, about 10.0, about 10.5, about 11.0, about 11.5,about 12.0, about 12.5, about 13.0, about 13.5, about 14.0, about 14.5,and about 15.0 parts by weight. Said at least one low-density copolymeris an ultra-low density copolymer of ethylene and said at least oneC₄-C₁₀ alpha-olefin, manufactured in a polymerization process using asingle-site polymerization catalyst, with a density in the range of fromabout 0.859 to about 0.905 g/cm³ and a melt-index in the range of fromabout 0.4 to about 1.1 dg/min. The density range can also be defined byany two numbers from about 0.859, about 0.860, about 0.861, . . . ,about 0.903, about 0.904, and about 0.905 g/cm³. Similarly, themelt-index range can be defined by any two numbers from about 0.4, about0.45, about 0.5, . . . , about 1.00, about 1.05, and about 1.10 dg/min.

In another embodiment, the foregoing ultra-low density copolymer ofethylene and at least one C₄-C₁₀ alpha-olefin, or said secondethylene-alpha-olefin copolymer is selected from ethylene/butene-1copolymers, ethylene/hexene-1 copolymers, ethylene/octene-1 copolymers,ethylene/octene-1/butene-1 terpolymers and ethylene/hexene-1/butene-1terpolymers.

The C₄-C₁₀ alpha-olefin also includes the cyclic counterparts.

The first interposed layer and/or the second interposed layer maycomprise more than one interposed layer. In one embodiment, the HDPEdistribution will be different between the different interposed layersof the first and/or the second interposed layer in such a way that theHDPE concentration by its percent weight of the total weight of thespecific interposed layer, increases as from the innermost interposedlayer (that layer which is more proximate to the core layer) to theoutermost interposed layer (that layer which is more proximate to thesealant layers). This embodiment is schematically described in FIG. 2.In FIG. 2, a multi-layer film is shown. The first and the secondinterposed layers, each, comprise four layers (F₁, F₂, F₃, F₄ and S₁,S₂, S₃, S₄ respectively). F₁ and S₁ are layers most proximate to thecore layer C. Similarly, F₄ and S₄ are proximate to the innersealant-layer (I) and the outer sealant layer (O). F₁, for example, has50% of HDPE, F₂ has 70% of HDPE, F₃ has 90% HDPE and F₄ has 100% HDPE,with the added restriction that the overall concentration of HDPE in thecombination of first and second interposed layers must be 78-100 wt %.In other embodiments, the HDPE weight percent range is defined by anytwo numbers from about 78, about 79, about 80, . . . , about 98, about99, and about 100 wt %. Similarly, the second interposed layers S₁-S₄can also have varying amounts of HDPE, increasing in concentration fromS₁ to S₄.

In one embodiment, the thickness of the first interposed layers, forexample, F₁, F₂, F₃, and F₄ is different. Similarly, the thickness ofthe second interposed layers, S₁, S₂, S₃, and S₄ can also be different.

In a preferred embodiment, the thickness of said at least one interposedlayer is from about 2 microns about 20 microns. The thickness of said atleast one interposed layer can be about 3, about 4, about 5, about 6,about 7, about 8, about 9, about 10, about 11, about 12, and 13, about14, about 15, about 16, about 17, about 18, about 19, or about 20microns.

Core Layer

The multi-layer film comprises at least one core layer that is adjacentto the first at least one interposed layer on one side and the second atleast one interposed layer on the opposite side. The core layercomprising polyethylene that is selected from the group consisting of:

-   -   (i) at least one low-density ethylene-alpha olefin copolymer,    -   (ii) a blend of said at least one low-density        ethylene-alpha-olefin copolymer and an at least one ethylene        homopolymer, wherein said ethylene homopolymer is made in a        high-pressure polymerization process; and    -   (iii) a blend of said at least one low-density        ethylene-alpha-olefin copolymer and an at least one ethylene        copolymer, wherein said ethylene copolymer is made in a        high-pressure polymerization process;

The ethylene homopolymer used in the at least one core layer, in oneembodiment, is made in a high-pressure polymerization process. One ormore ethylene homopolymers can be used in the core layer. In oneembodiment, the weight percent of the ethylene homopolymer is from 10 toabout 50 parts by weight of said at least one core layer. In otherembodiments the weight percent of the ethylene homopolymer range isdefined by any two numbers from about 10, about 11, about 12, . . . ,about 48, about 49, and about 50 parts by weight of said at least onecore layer. The ethylene homopolymer has a density in the range of fromabout 0.918 to about 0.923 g/cm³, and a melt-index in the range of fromabout 0.1 to about 1.1 dg/min. The density range can also be defined byany two numbers from about 0.918, about 0.919, about 0.920, about 0.921,about 0.922, and about 0.923 g/cm³. Similarly, the melt-index range canalso be defined by any two numbers, namely, about 0.1, about 0.2, about0.3, about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, about 0.9,about 1.0, and 1.1 dg/min.

In another embodiment, more than one ethylene homopolymers may be usedin one or more layers of the core layer. The number of ethylenehomopolymers and the type of ethylene homopolymers may vary between anycore layers. For example, a multi-layer film comprises three core layers(C₁, C₂, and C₃). In one embodiment, C₁, C₂, and C₃, for example, mayhave only one and the same ethylene homopolymer. In another embodiment,C₁, C₂, and C₃ may have the different ethylene homopolymers. In anotherembodiment, for example, C₁ may have two ethylene homopolymers while C₂may have three ethylene homopolymers, while C₃ may have no ethylenehomopolymer. Two ethylene homopolymers may differ from each other byhaving different densities, different melt-indices, different molecularweights, or different branch structures.

The ethylene copolymer used in the at least one core layer, in oneembodiment, is made in a high-pressure polymerization process. One ormore ethylene copolymers can be used in the at least one core layer. Inone embodiment, the weight percent of the ethylene homopolymer is from10 to about 50 parts by weight of said at least one inner sealant layeror said at least one outer sealant layer. The ethylene copolymer has adensity in the range of from about 0.930 to about 0.960 g/cm³, and amelt-index in the range of from about 0.1 to about 10 dg/min. Thedensity range can also be defined by any two numbers from about 0.930,about 0.935, about 0.940, about 0.945, about 0.950, about 0.955, andabout 0.960 g/cm³. Similarly, the melt-index range can also be definedby any two numbers, namely, about 0.1, about 0.2, about 0.3, . . . ,about 9.8, about 9.9, and about 10.0 dg/min.

In another embodiment, more than one ethylene copolymers may be used inone or more layers of the core layers. The number of ethylene copolymersand the type of ethylene copolymers may vary between any two corelayers. For example, a multi-layer film comprises three core layers (C₁,C₂, and C₃). In one embodiment, C₁, C₂, and C₃, for example, may haveonly one and the same ethylene copolymer. In another embodiment, forexample, C₁ may have two ethylene copolymers while C₂ may have threeethylene copolymers, while C₃ may have no ethylene copolymer. Twoethylene copolymers may differ from each other by having differentdensities, different melt-indices, different molecular weights, ordifferent branch structures.

The comonomer of ethylene in the ethylene copolymer described in theforegoing can be chosen from polar monomers such as vinyl acetate,acrylic acid, methacrylic acid, and vinyl methacrylate, wherein theethylene copolymer is manufactured in a high-pressure polymerizationprocess. The concentration of polar comonomer must be kept relativelylow in order that the copolymer has good compatibility with the majorpolyethylene component of the sealant layer(s). For example, ethylenevinyl acetate copolymers should contain less than or equal to 15wt %vinyl acetate. Otherwise, poor optical appearance, and even poorintra-layer adhesion, can result.

In another embodiment, the at least one core layer comprises at leastone low-density ethylene-alpha-olefin copolymer, which may be foundalone or in a blend form with an ethylene homopolymer described supra,or ethylene copolymer described supra. Such low-density ethylenealpha-olefin copolymer, in a preferred embodiment, is found as acopolymer that is from about 35 to about 85 parts by weight of the atleast one core layer weight. The copolymer range can also be defined byany two numbers from about 35, about 36, about 37, . . . , about 83,about 84, and about 85 parts by weight of the at least one core layerweight. The copolymer is a low-density copolymer of ethylene and an atleast one C₄-C₁₀ alpha-olefin manufactured in a polymerization processusing a single-site polymerization catalyst, with a density in the rangeof from about 0.909 to about 0.935 g/cm³ and a melt-index in the rangeof from about 0.5 to about 1.5 dg/min. The density range can also bedefined by any two numbers from about 0.909, about 0.910, about 0.911, .. . , about 0.933, about 0.934, and about 0.935 g/cm³. Similarly, themelt-index range can be defined by any two numbers from about 0.5, about0.6, about 0.7, . . . , about 1.3, about 1.4, and about 1.5 dg/min. Inaddition, said embodiment further comprises, from about 0 to about 15parts by weight of an additional at least one low-density copolymer ofethylene and an at least one C₄-C₁₀ alpha-olefin. In other embodiments,the weight percent range can be defined by any two numbers from about0.0, about 0.5, about 1.0, about 1.5, about 2.0, about 2.5, about 3.0,about 3.5, about 4.0, about 4.5, about 5.0, about 5.5, about 6.0, about6.5, about 7.0, about 7.5, about 8.0, about 8.5, about 9.0, about 9.5,about 10.0, about 10.5, about 11.0, about 11.5, about 12.0, about 12.5,about 13.0, about 13.5, about 14.0, about 14.5, and about 15.0 parts.Said additional at least one low-density copolymer is an ultra-lowdensity copolymer of ethylene and said at least one C₄-C₁₀ alpha-olefin,manufactured in a polymerization process using a single-sitepolymerization catalyst, with a density in the range of from about 0.859to about 0.905 g/cm³ and a melt-index in the range of from about 0.4 toabout 1.1 dg/min. Similarly, the density range can also be defined byany two numbers from about 0.859, about 0.860, about 0.861, . . . ,about 0.903, about 0.904, and about 0.905 g/cm³. Similarly, themelt-index range can be defined by any two numbers from about 0.4, about0.45, about 0.50, . . . , about 1.0, about 1.05, and about 1.10 dg/min.

In another embodiment, the foregoing low-density copolymer of ethyleneand at least one C₄-C₁₀ alpha-olefin, or said at least one ultra-lowdensity copolymer of ethylene and at least one C₄-C₁₀ alpha-olefin isselected from ethylene/butene-1 copolymers, ethylene/hexene-1copolymers, ethylene/octene-1 copolymers, ethylene/octene-1/butene-1terpolymers and ethylene/hexene-1/butene-1 terpolymers.

The C₄-C10 alpha-olefin also includes the cyclic counterparts.

Therefore generally, the present invention also provides a multilayerfilm formed from a layer of a sealant film and a layer of a film havinga higher stiffness than the sealant layer, said layer of higherstiffness being formed from a polymer having a melting point of not morethan 140° C.

In preferred embodiments of the multilayer film of the presentinvention, the film has a stiffness of at least 20 000 psi(approximately 135 MPa), and especially at least 25 000 psi(approximately 170 MPa). In other embodiments, the multilayer film has astiffness of at least 21,000 psi, 22,000 psi, 23,000 psi, or 24,000 psi.

The present invention also provides a pouch containing a flowablematerial, said pouch being made from the previously describedmulti-layer film in tubular form and having transversely heat sealedends.

The present invention further provides a process for making pouchesfilled with a flowable material, using a vertical form, fill and seal(“VFFS”) apparatus, in which process each pouch is made from a flat webof film by forming a tubular film therefrom with a longitudinal seal andsubsequently flattening the tubular film at a first position andtransversely heat sealing said tubular film at the flattened position,filling the tubular film with a predetermined quantity of flowablematerial above said first position, flattening the tubular film abovethe predetermined quantity of flowable material at a second position andtransversely heat sealing said tubular film at the second position, theimprovement comprising making the pouches from a flat web of a film madefrom a multilayer film described previously. The VFFS processes and itsmodifications are described in U.S. Pat. No. 5,538,590 and areincorporated by reference herein in their entirety.

Although melt-index ranges are specified herein, it is understood thatthe polymers have melt indices typical of film-grade polymers.

The multi-layer films of the present invention have the ability to forma lap seal as well as a fin seal. They also substantially reduce thecurl in the laminate. In addition, although the non-sealant layer may bea layer of higher stiffness comprising HDPE that has a melting point ofnot more than 140° C., that layer will be particularly described hereinwith reference to a layer of polyethylene.

Catalysts

In the present invention, linear ethylene based polymers, copolymers,terpolymers, etc. are made using the Ziegler-Natta catalysts,single-site catalysts, the metallocene catalysts, or a combination ofsuch catalysts, depending upon the need for the type of polymer.

High pressure low density polyethylene, or HP-LDPE, was the originalpolyethylene to be polymerized from ethylene monomer. The “highpressure” refers to the rather extreme polymerization processconditions. Generally, “low density” refers to the 0.918-0.930 g/cm³range of polyethylene densities. The HP-LDPE molecules have complexbranching patterns, with no easily distinguishable backbone. The polymermolecules are composed of a whole network of branches of various lengthsfrom short to long. The present invention makes use of HP-LDPE polymerswhich are relatively high in average molecular weight, or low inmelt-index (0.1-1.1 dg/min).

Development of the Ziegler-Natty catalysts allowed polyethylene (andpolypropylene) to be polymerized under less extreme conditions, and, inparticular, at lower pressures. The first Zeigler-Natta-catalyzedpolyethylene was distinctly different from HP-LDPE in two ways: themolecules were very linear in nature, with essentially no branches, andthe polyethylene could have a very high density (˜0.960 g/cm³) becausethe linear molecules could pack together closely to form extensivecrystalline domains in the solid polymer.

High density polyethylene, in general, has a density of at least 0.935g/cm³ but, in this invention, the HDPE must have a density of greaterthan 0.950 g/cm³ in order to provide sufficient stiffness, but less thanor equal to about 0.970 g/cm³. In other embodiments of the invention,the HDPE density is within the range defined by any two numbers fromabout 0.950, about 0.951, about 0.952, . . . , about 0.968, about 0.969,and about 0.970 g/cm³. In addition, the high density polyethylene has amelt-index of less than 1.05 dg/min, but more than 0.3 dg/min HDPE inthe melt-index range of 0.01 to 0.3 dg/min, which is generallyclassified as high molecular weight high density polyethylene, HMW-HDPE,has melt flow characteristics, which are unsuitable in the presentinvention. In other embodiments, the HDPE has a melt-index in the rangedefined by any two numbers from about 0.3, about 0.35, about 0.40, . . ., about 0.95, about 1.00, and about 1.05 dg/min.

As the use of Zeigler-Natta catalysts continued, it was discovered thatthe density of the linear polyethylene could be controlled and loweredby introducing a comonomer, in addition to the ethylene, for example,butene, hexene or octene. In fact, any low molecular-weight alpha-olefinsuitably reacts with ethylene and breaks up the regularity of the linearchain development during polymerization—the alpha-olefin double bond atthe end of the molecule opens up as it reacts, allowing the carbons oneither side to become part of the linear backbone, with the remainder ofthe alpha-olefin molecule becoming a short side chain. The short sidechain disrupts polymer crystallization and lowers density: the more sidechains that are present, the lower the polymer density.

Processes for the commercial manufacture of linear polyethylene havebeen known for more than thirty years. Such processes may be operated attemperatures above the solubilization temperature of the polymer inwhich event the polymer remains in solution, or the processes may beoperated below the solubilization temperature in which event the polymerremains as a slurry in the polymerization solvent. Processes are alsoknown in which the polymerization is conducted in the gas phase in theabsence of solvent. The catalysts used are frequently based on titaniumand are referred to as coordination catalysts; such catalysts may alsobe described as multi-site catalysts or heterogeneous catalysts. Thepolymer obtained is linear in nature, as opposed to the branched natureof high pressure polyethylene Linear low density polyethylene isobtained by the co-polymerization of ethylene with at least one C₄-C₁₀alpha-olefin hydrocarbon comonomer, examples of which include butene-1,hexene-1 and octene-1. The linear low density polyethylene has a densityin the range of 0.909 to 0.935 g/cm³, preferably 0.912 to 0.930 g/cm³and especially in the range of 0.912 to 0.926 g/cm³. In otherembodiments, the linear low density polyethylene has a density in therange defined by any two numbers from about 0.909, about 0.910, about0.911, . . . , about 0.933, about 0.934, and about 0.935 g/cm³. Inaddition the polymer has a melt-index in the range of 0.3 to 10.0dg/min, preferably 0.3 to 2.0 dg/min and especially in the range of 0.5to 1.5 dg/min. In other embodiments, the melt-index is in the rangedefined by any two numbers from about 0.3, about 0.4, about 0.5, . . . ,9.8, about 9.9, and about 10.0 dg/min.

Traditional Ziegler-Naha catalysts produce heterogeneous LLDPE polymers.This is because both the molecular weight and the extent of comonomerincorporation vary considerably from molecule to molecule. Theheterogeneity of the Zeigler-Natta polymerized LLDPE polyethylene can bedetected from the relatively broad, multi-peak, DSC melting (orfreezing) curve, as illustrated in FIG. 3. The peak melting is observedat about 125° C. with a lower-temperature broader peak. High molecularweight molecules, with very little incorporated comonomer, produce themajor peak (very similar to the original linear polyethylenehomopolymer). Melting copolymers (with a wide range of molecular weightsand comonomer contents) produce the broader peak. The lowest meltingportion, also known as the grease fraction, comprises lowmolecular-weight molecules. Low molecular-weight molecules incorporatehigher number of comonomers that increases branch concentration. Thegrease fraction lubricates the higher molecular-weight linearpolyethylene, improving its extrudability. As the grease fractionincreases, however, the polymer clumps together impeding the pelletizedpolymer flow. Therefore, the use of Zeigler-Natta-catalyzed polyethylenehas generally been limited to higher than 0.912 g/cm³ density polymers.

It was theorized that different Zeigler-Natta catalyst sites encouragedgrowth of different types of polymer chains resulting in heterogeneouspolyethylene. Therefore, single site catalysts were developed, whichwould produce homogeneous LLDPE polymers, which were more uniform withrespect to molecular weight distribution and comonomer incorporation.Thus, polyethylene densities as low as 0.800 g/cm³ to as high as 0.965g/cm³ are now possible. However, the latest expansion of the densityrange (below about 0.912 g/cm³) has taken place only since thedevelopment of the single-site catalyst, also known in some versions asthe Metallocene catalyst.

U.S. Pat. No. 3,645,992 describes single-site catalysts capable ofproducing homogeneous polyethylenes. The homogeneity occurs because themolecules are much more similar to one another in terms of molecularweight and comonomer concentration. In other words, the high-molecularweight tail and the grease fraction are both largely eliminated with theDSC melting curve showing a single melting peak, as a result, asillustrated in FIG. 4. Cleanly flowing pellets, with no greasy feel,could be produced with densities as low as 0.800 g/cm³. These catalystsare called single-site catalysts because all catalyst sites encouragethe growth of relatively similar polymer chains.

“Single-site catalysts” include metallocene or constrained-geometrycatalysts. Metallocene catalysts are organometallic co-ordinationcompounds obtained as a cyclopentadienyl (Cp) derivative of a transitionmetal or metal halide. The metal bonds to the Cp ring by electronsmoving in orbitals extending above and below the plane of the ring(pi-bond). Metallocene catalysts systems are extremely sensitive to thegeometry of the catalytic site at the transition metal (the“single-site”). Examples of single-site catalysts include Cp₂TICl₂,Cp₂ZrCl₂, Cp₂ HfCl₂, (C₅(CH₃)₂)₃TiCl₂, PH₂Me (Ind)₂ZrCl₂, [Me₄CpSi(Me)₂N(t-Bu)]TiCH₂[o-PhN(Me₂], Cp₂Fe B(C₂F₂)₄.

The ethylene copolymer made with single-site catalyst may be obtainedusing a variety of polymerization processes of the type described abovefor the manufacture of linear low density polyethylene, for example,processes that operate in solution, in the gas phase and as a slurryprocess; references to the use of single site catalysts inpolymerization processes is made in Modern Plastics, p. 15, May 1993,Plastics Focus Vol. 25, No. 12, Jun. 21, 1993 and in Exxon ChemicalExact Facts, Vol. 1, No. Feb. 1, 1993. Such polymers are obtained by thecopolymerization of ethylene with at least one C₄-C₁₀ alpha-olefinhydrocarbon comonomer, examples of which include butene-1, hexene-1, andoctene-1. The catalyst used is a so-called single-site catalyst, certainof which may also be referred to as metallocene or constrained geometrycatalysts.

In the present invention, if the linear polyethylene obtained with thesingle site catalyst is a low-density copolymer of ethylene and an atleast one C₄-C₁₀ alpha-olefin, then it has a density in the range of0.905 to 0.935 g/cm³, preferably in the range 0.909 to 0.930, andespecially in the range 0.912 to 0.926 g/cm³. In other embodiments, thedensity range can be defined by any two numbers from about 0.905, about0.906, about 0.907, . . . , about 0.933, about 0.934, and about 0.935g/cm³. In addition the low density copolymer has a melt-index in therange of 0.3 to 10.0 dg/min, preferably 0.3 to 2.0 dg/min and especiallyin the range of 0.5 to 1.5 dg/min. In other embodiments, the melt-indexis in the range defined by any two numbers from about 0.3, about 0.4,about 0.5, . . . , about 9.8, about 9.9, and about 10.0 dg/min.

If the linear polyethylene is used as a minor blend component, and is anultra-low-density copolymer of ethylene and an at least one C₄-C₁₀alpha-olefin, then it preferably has a density in the range of 0.8 to0.909 g/cm³, moreover in the range of 0.859 to 0.905 g/cm³, andespecially in the range of 0.859 to 0.888 g/cm³. In other embodiments,the density range can be defined by any two numbers from about 0.800,about 0.801, about 0.803, . . . , about 0.907, about 0.908, and about0.909 g/cm³. In addition, the ultra-low-density polymer preferably has amelt-index of less than 5 dg/min, particularly in the range of 0.4 to1.1 dg/min and especially in the range of 0.4 to 0.6 dg/min. In otherembodiments, the melt-index is in the range defined by any two numbersfrom about 0.4, about 0.5, about 0.6, . . . , about 0.9, about 1.0, andabout 1.1 dg/min. In either case, the preferred copolymers includeethylene/butene-1, ethylene/hexene-1, ethylene/octene-1 andethylene/hexene-1/butene-1 terpolymers.

The blends useful in the present invention may be made by blending theconstituents prior to feeding to the hopper of a film extruder, or maybe made by blending the constituents at the time of extrusion just priorto remelting in the extruder, or alternatively the constituents may bemelt blended in the extruder.

The ethylene/alpha-olefin copolymer or blend of ethylene/alpha-olefincopolymers, for example, in pellet form, may be extruded into film formusing known techniques. One preferred method of manufacturing film isthe so-called blown film process. The film, after manufacture, is slitlongitudinally into appropriate widths. The width is selected on thebasis of the diameter of the tube to be formed on the vertical form,fill and seal apparatus. The preferred method of manufacture of amultilayer film is by using a blown film co-extrusion process, althoughother methods of manufacture of the film may be used.

The multilayer film of the invention is particularly useful in theformation of pouches, especially using a form, fill and seal apparatus.The pouches of the present invention may be used in the packaging offlowable materials, for example, liquids, as defined above. Inparticular, the pouches may be used in the packaging of milk.

In particular, the multilayer film provides increased stiffness,compared to the monolayer sealant film, increased clarity compared toHDPE film, and further improves efficiencies in the runnability andsealability of monolayer and prior art multilayer films as describedherein.

Other Additives

In the present invention, sealant layers can have a combined weight of0-10 wt % of extrusion aid masterbatches including slip, antiblock andprocess aid. Interposed layers and core layers can have 0-2 wt % of slipmasterbatches.

It will be understood by those skilled in the art that additives such asantioxidants, UV stabilizers, anti-block agents, and slip additives, maybe added to the polymers from which the pouches of the present inventionare made. It will be understood by those skilled in the art thatadditives such as antioxidants, UV stabilizers, anti-block agents, andslip additives, may be added to the polymers from which the pouches ofthe present invention are made. Optionally, the inner-sealant layer, theouter-sealant layer, the core and/or the first or the second interposedlayer may further comprise one or several additives useful to makeeasier the processing of a film in a VFFS system, such as, for example,polymer processing aids concentrate, and/or slip/antiblock concentrates.Any of such additives well known to person skilled in the art can beused. Advantageously, the following additives are particularlypreferred.

Slip Agent

The preferred range of the slip agent is from about 200 to 2000 ppm. Apreferred slip agent is erucamide or other fatty acid amide such asoleamide. The slip agent lowers the coefficient friction of the film andallows it to slide readily over various surfaces.

Anti-Blocking Agent

1000 to 5000 ppm of any film anti-blocking agent, well known to skilledworkman, maybe added to the film layers, especially the outer and innerskin layers of the film. Preferably from 1000 to 8000 ppm of ananti-blocking material such as diatomaceous earth, synthetic silica ortalc will be added to the inner and outer layers of the film. Theanti-blocking material is particularly useful in reducing thecoefficient of friction between the film and the metallic surfaces overwhich the film is drawn during the VFFS process.

Processing Aid

50 to 1000 ppm of any processing aid, well known to skilled workman,preferably and not limitatively containing a fluoro-elastomer basedpolymer maybe added to outer and inner skin layers of the film.

Pouch-Making Processes

Pouch-making processes for VFFS are known in the art, for example, U.S.Patent Publication No. 2007/0254119, which is incorporated by referenceherein. The invention at hand also relates to a process for makingpouches filled with a flowable material, generally using a VFFSapparatus, wherein each pouch is made from a flat web of film by thefollowing steps:

-   -   (I) forming a tubular film therefrom with a longitudinal seal        and subsequently flattening said tubular film at a first        position;    -   (II) transversely heat-sealing said tubular film at the        flattened position;    -   (III) filling said tubular film with a predetermined quantity of        flowable material above said first position;    -   (IV) flattening said tubular film above the predetermined        quantity of flowable material at a second position; and    -   (V) transversely heat sealing said tubular film at said second        position,

wherein said pouches are made from a flat web of film made from amulti-layer film, comprising the following layers in order of an atleast one inner sealant-layer to an at least one outer sealant-layer:

-   -   (A) said at least one inner sealant-layer comprising        polyethylene that is selected from the group consisting of:        -   (i) an at least one low-density ethylene-alpha-olefin            copolymer,        -   (ii) a blend of said at least one low-density            ethylene-alpha-olefin copolymer and an at least one ethylene            homopolymer, wherein said ethylene homopolymer is made in a            high-pressure polymerization process; and        -   (iii) a blend of said at least one low-density            ethylene-alpha-olefin copolymer and an at least one ethylene            copolymer, wherein said ethylene copolymer is made in a            high-pressure polymerization process;    -   (B) a first at least one interposed layer adjacent to said at        least one inner sealant-layer, said first at least one        interposed layer comprising:        -   (i) an at least one high-density polyethylene, or a blend of            said at least one high-density polyethylene and at least one            ethylene-alpha-olefin copolymer;        -   (ii) optionally, an ethylene homopolymer made in a            high-pressure polymerization process;        -   (iii) optionally, an ethylene copolymer made in a high            pressure polymerization process; and        -   (iv) optionally, a second ethylene-alpha-olefin copolymer            that is not the same as said at least one            ethylene-alpha-olefin copolymer in (B)(i);        -   wherein the centerline of said first at least one interposed            layer is closer to the centerline of said at least one inner            sealant-layer than to the centerline of said multi-layer            film;    -   (C) at least one core layer, adjacent to said first at least one        interposed layer, said at least one core layer comprising        polyethylene that is selected from the group consisting of:        -   (i) at least one low-density ethylene-alpha olefin            copolymer,        -   (ii) a blend of said at least one low-density            ethylene-alpha-olefin copolymer and an at least one ethylene            homopolymer, wherein said ethylene homopolymer is made in a            high-pressure polymerization process; and        -   (iii) a blend of said at least one low-density            ethylene-alpha-olefin copolymer and an at least one ethylene            copolymer, wherein said ethylene copolymer is made in a            high-pressure polymerization process;    -   (D) a second at least one interposed layer adjacent to said at        least one core layer, said second at least one interposed layer        comprising:        -   (i) an at least one high-density polyethylene, or a blend of            said at least one high-density polyethylene and at least one            ethylene-alpha-olefin copolymer;        -   (ii) optionally, an ethylene homopolymer made in a            high-pressure polymerization process;        -   (iii) optionally, an ethylene copolymer made in a high            pressure polymerization process; and        -   (iv) optionally, a second ethylene-alpha-olefin copolymer            that is not the same as said at least one            ethylene-alpha-olefin copolymer in (D)(i);        -   wherein the centerline of said second at least one            interposed layer is closer to the center-line of said at            least one outer sealant-layer than to the centerline of said            multi-layer film; and    -   (E) said at least one outer sealant-layer, comprising        polyethylene that is selected from the group consisting of:        -   (i) an at least one low-density ethylene-alpha-olefin            copolymer;        -   (ii) a blend of said at least one low-density            ethylene-alpha-olefin copolymer and an at least one ethylene            homopolymer, wherein said ethylene homopolymer is made in a            high-pressure polymerization process; and        -   (iii) a blend of said at least one low-density            ethylene-alpha-olefin copolymer and an at least one ethylene            copolymer, wherein said ethylene copolymer is made in a            high-pressure polymerization process;

wherein said multi-layer film thickness is in the range of from about 35microns to about 66 microns;

wherein a combined thickness of said first at least one interposed layerand said second at least one interposed layer is in the range of fromabout 10% to about 27% of the total thickness of said multi-layer film;

wherein a combined thickness of said inner sealant-layer and said outersealant-layer is in the range of from about 10% to about 27% of thetotal thickness of said multi-layer film; and

wherein said at least one high-density polyethylene in said first atleast one interposed layer and said second at least one interposed layerhas a density of at least of about 0.950 g/cm³ and a melt-index of lessthan 1.05 dg/min.

Abbreviations

BUR Blow-up ratio

EVA Ethylene-vinyl acetate

HDPE High-density polyethylene

HP-LDPE High-pressure, low-density polyethylene

LLDPE linear low-density polyethylene

MWD/SCBD Molecular weight distribution/Short-chain branchingdistribution

ULDPE Ultra low-density polyethylene

VA Vinyl acetate

VFFS Vertical Form, Fill, and Seal

Experimental

In the present set of experiments, generally, a multi-layer film is madeusing film extrusion processes that are well-known to the filmmanufacturing industry. The multi-layer film is extruded on a five-layerblown-film co-extrusion line. Films from the resin compositions of thisinvention can also be made using other film extrusion processes whichare well-known to the film manufacturing industry.

In one embodiment of the invention, which is a five-layer multi-layerfilm, the inner sealant-layer is designated as Layer A, the firstinterposed layer is designated as Layer B, the core layer is designatedas Layer C, the second interposed layer is designated as Layer D, andthe outer sealant-layer is designated as Layer E.

Three extruders (E_(A), E_(B), E_(C)) feed an eight-inch diametercircular die used for preparing the film. Extruder EA feeds the outersealant-layer (Layer E) and the inner sealant-layer (Layer A). The“sealant layer” extruder, E_(A), is a 2-inch diameter, single-screwextruder. Extruder E_(C) feeds the first interposed layer (Layer B), andthe second interposed layer (Layer D). The “interposed layer” extruder,E_(C), is also a 2-inch diameter, single-screw extruder. Extruder E_(B)feeds the core layer (Layer C). The “core layer” extruder E_(B) is alarger 4-inch diameter, single-screw extruder.

The co-extrusion line includes an oscillating nip, a corona-treater, anedge guide, and a back-to-back winder with slit-in-line that is capableof being surface-driven or centre-driven. The width of the tower nip andwinder also allow for blow-up ratios (“BUR”) up to about 4:1.Preferably, the BUR range is from 1.5 to 2.8, which provides a stableprocess and good film quality. The melt processing temperatures of theresins in the extruders ranged from 150° C. to 260° C. Processingadditives such as slip and antiblock are incorporated into the resins assupplied or otherwise dry-blended in the form of additive concentrates,or melt-compounded into the resins through melt-compounding processes.

In one embodiment, the films are made at a BUR of 2:1. The films arewound as a flattened tube and slit to a narrower width.

For illustrative purposes, films with 17 different EXAMPLE resin recipesare manufactured on the co-extrusion line as described. The films aremade with a total thickness of 52 microns and the following layerthicknesses: A=4 microns, B=6 microns, C=32 microns, D=6 microns and E=4microns.

The films are run on the Prepac IS-7E filler to assess runnability, tomake pouches for evaluating in a pitcher, and to make pouches for apouch drop test. Pouches are made from the above-described multi-layerfilms (also see multi-layer film formulations, infra) using the VFFSprocess. It is normal to make pouches containing 1.3 liters of water, ata temperature of 4.0+/−0.5° C., from a 24-cm wide film web; however, itis possible to make other pouch sizes if this is more relevant to thespecific end-use. The Prepac IS-7E vertical form, fill and sealapparatus is normally equipped with an insulated transverse sealing jaw(U.S. Pat. No. 5,538,590) and easy mount transverse sealing element(PCT/CA98/00066 or equivalent). The web of film is formed into acontinuous tube with a lap seal, said tube having an inside diameter ofapproximately 9.8 cm. The operation of the vertical and transversesealing elements should be optimized for the particular film type andthickness used. It will be recognized that the sealing conditions (forexample, amperage, voltage, dwell time) depend on the gauge and meltingcharacteristics of the film. For example, a 50 μm film would requirelower amperage and/or voltage, as controlled by the rheostat on theapparatus, than would a 75 μm film. Typically such a change in filmthickness requires an adjustment of approximately 10% of the rheostatrange.

The drop test can be a constant height pouch drop test, or a Brucetonstair drop test, where the drop height is varied in a systematic way.Both procedures are adaptations of ASTM D5276: Drop Test of LoadedContainers by Free Fall. It should be verified that the pouches in thedifferent batches have very similar mean and standard deviation valuesfor weight, length, and headspace.

Constant Height Drop Test (Version of ASTM D5276 A2.2.1)

To compare the performance of one pouch film against another, at least200 well-made pouches should be manufactured from each film and droppedfrom a constant initial height in the range 10-15 feet. The pouchesshould be dropped before the water in them has had a chance to warm upappreciably. Each pouch is positioned with the longitudinal axis of thetube i.e. pouch, coincident with an imaginary horizontal line, thebottom surface of the pouch at the initial drop height, and the verticalseal facing upwards. In this orientation, the pouch is dropped onto astainless steel sheet, and then inspected visually and tactilely forleakers. Any pouch, from which water flows or weeps after the pouch hasbeen dropped, is termed a “leaker”. The number of leakers, expressed asa percentage of the total number of pouches dropped is the M(1.3)-testvalue for the particular film being tested, where 1.3 denotes the pouchsize in liters.

Bruceton Stair Drop Test (Version of ASTM D5276 A2.4.2)

The Bruceton Stair test is more discriminating, and requires only 40-50well-made pouches. The first pouch is positioned with the longitudinalaxis of the tube i.e. pouch, coincident with an imaginary horizontalline, the bottom surface of the pouch at a suitable initial drop height,say 8 feet, and the vertical seal facing upwards. In this orientation,the pouch is dropped onto a stainless steel sheet, and then inspectedvisually and tactilely for leakers. If the first pouch survives the droptest intact without leaking water, then a new pouch is selected anddropped from a height of an additional 0.5 feet, that is, 8.5 feet. Onthe other hand, if the first pouch is a leaker, then a new pouch isselected and dropped from a height, which is lower by 0.5 feet, that is7.5 feet. The testing continues, using a new pouch for every drop, untilat least 5 passes and 5 failures have occurred in the height range whereboth passes and failures are occurring. The 50% failure height is thencalculated using the statistical method of ASTM D 5628.

Extrusion Aid Masterbatches

For the experimental examples described below, extrusion aids such asslip and anti-block are purchased as pelletized masterbatches fromIngenia Polymers (Houston, Tex.). The active ingredient is compoundedinto a polyethylene carrier resin, usually a 2-10 MI LLDPE resin.

TABLE 1 Masterbatch Active Ingredient Concentration Function IngeniaIP1065 erucamide 5 wt % slip Ingenia IP1061A oleamide 5 wt % slipIngenia IP1142 fluoropolymer cpd 4 wt % metal coating Ingenia IT719 talc30 wt %  antiblock Ingenia IP1051 silica 25 wt %  antiblock

A pellet blend of the major polyethylene resins, and thesemasterbatches, is fed to each extruder of the co-extrusion line. Thevarious components of the pelletized mixture are fed into the mainextruder hopper via satellite blenders, the rates of which can be set toachieve the desired mix ratio.

EXAMPLE 1

Layers of the Multi-layer Film 1 are prepared with the resins andadditives shown in Table 1.

TABLE 1 Formulation for Multi-layer Film 1 Catalyst in Resin ResinGrade/ Weight % Polymer Resin Manu- Density Melt-index Trade Name*Supplier of Layer Type Comonomer facture MWD/SCBD g/cm³ deci g/min Inner& Outer Sealant-Layer (A & E); Extruder E_(A) Marflex D143 Chevron-86.70 LLDPE Hexene Single Site Homogeneous 0.916 1.40 Phillips Engage8150 Dow 9.0 ULDPE Octene Single Site Homogeneous 0.868 0.5  IP1065Ingenia 1.6 LLDPE — — — 0.920 2-10 MI carrier carrier IT 719 Ingenia 1.3LLDPE — — — 1.140 2-10 MI carrier carrier First & SecondInterposed-Layer (B & D); Extruder E_(C) Sclair 19C Nova 88.20 HDPE NoneZiegler-Natta Heterogeneous 0.954 0.95 Elvax 3135X DuPont 10.0 EVA Vinylacetate High Pressure Heterogeneous 0.930 0.35 IP1065 Ingenia 1.6 LLDPE— — — 0.920 2-10 MI carrier carrier Core-Layer (C); Extruder E_(B)Marflex D143 Chevron- 68.70 LLDPE Hexene Single Site Homogeneous 0.9161.40 Phillips Elvax 3135X DuPont 30 EVA Vinyl acetate High PressureHeterogeneous 0.930 0.35 IP1065 Ingenia 1.6 LLDPE — — — 0.920 2-10 MIcarrier carrier

EXAMPLE 2

Layers of the Multi-layer Film 2 are prepared with the resins andadditives shown in Table 2.

TABLE 2 Formulation for Multi-layer Film 2 Catalyst in Resin ResinGrade/ Weight % Polymer Resin Manu- Density Melt-index Trade Name*Supplier of Layer Type Comonomer facture MWD/SCBD g/cm³ deci g/min Inner& Outer Sealant-Layer (A & E); Extruder E_(A) Marflex D143 Chevron-86.70 LLDPE Hexene Single Site Homogeneous 0.916 1.40 Phillips Engage8150 Dow 9.0 ULDPE Octene Single Site Homogeneous 0.868 0.5  IP1065Ingenia 3.0 LLDPE — — — 0.920 2-10 MI carrier carrier IT 719 Ingenia 1.3LLDPE — — — 1.140 2-10 MI carrier carrier First & SecondInterposed-Layer (B & D); Extruder E_(C) Sclair 19C Nova 88.20 HDPE NoneZiegler-Natta Heterogeneous 0.954 0.95 Elvax 3135X DuPont 10.0 EVA Vinylacetate High Pressure Heterogeneous 0.930 0.35 IP1065 Ingenia 1.8 LLDPE— — — 0.920 2-10 MI carrier carrier Core-Layer (C); Extruder E_(B)Marflex D143 Chevron- 68.70 LLDPE Hexene Single Site Homogeneous 0.9161.40 Phillips Elvax3135X DuPont 30 EVA Vinyl acetate High PressureHeterogeneous 0.930 0.35 IP1065 Ingenia 1.3 LLDPE — — — 0.920 2-10 MIcarrier carrier

EXAMPLE 3

Layers of the Multi-layer Film 3 are prepared with the resins andadditives shown in Table 3.

TABLE 3 Formulation for Multi-layer Film 3 Resin Resin Grade/ Weight %Polymer Catalyst in Density Melt-index Trade Name* Supplier of LayerType Comonomer Resin Manufacture MWD/SCBD g/cm³ deci g/min Inner & OuterSealant-Layer (A & E); Extruder E_(A) Surpass FPs016C Nova 85.50 LLDPEOctene Single Site Homogeneous 0.916 0.65 Engage 8150 Dow 9.0 ULDPEOctene Single Site Homogeneous 0.868 0.5  IP1065 Ingenia 3.0 LLDPEcarrier — — — 0.920 2-10 MI carrier IT 719 Ingenia 1.3 LLDPE carrier — —— 1.140 2-10 MI carrier IP1142 Ingenia 1.2 LLDPE carrier — — — 0.9302-10 MI carrier First & Second Interposed-Layer (B & D); Extruder E_(C)Sclair 19C Nova 88.20 HDPE None Ziegler-Natta Heterogeneous 0.954 0.95Elvax 3135X DuPont 10.0 EVA Vinyl acetate High Pressure Heterogeneous0.930 0.35 IP1065 Ingenia 1.8 LLDPE carrier — — — 0.920 2-10 MI carrierCore-Layer (C); Extruder E_(B) Surpass FPs016C Nova 68.7 LLDPE OcteneSingle Site Homogeneous 0.916 0.65 Elvax 3135X DuPont 30 EVA Vinylacetate High Pressure Heterogeneous 0.930 0.35 IP1065 Ingenia 1.3 LLDPEcarrier — — — 0.920 2-10 MI carrier

EXAMPLE 4

Layers of the Multi-layer Film 4 are prepared with the resins andadditives shown in Table 4.

TABLE 4 Formulation for Multi-layer Film 4 Resin Resin Grade/ Weight %Polymer Catalyst in Density Melt-index Trade Name* Supplier of LayerType Comonomer Resin Manufacture MWD/SCBD g/cm³ deci g/min Inner & OuterSealant-Layer (A & E); Extruder E_(A) Elite 5400G Dow 85.20 LLDPE OcteneSingle Site Heterogeneous 0.916 1.0  Reactor Blend Engage 8150 Dow 9.0ULDPE Octene Single Site Homogeneous 0.868 0.50 IP1065 Ingenia 3.0 LLDPEcarrier — — — 0.920 2-10 MI carrier IT 719 Ingenia 1.3 LLDPE carrier — —— 1.140 2-10 MI carrier IP1142 Ingenia 1.5 LLDPE carrier — — — 0.9302-10 MI carrier First & Second Interposed-Layer (B & D); Extruder E_(C)Elite 5960G Dow 83.70 HDPE None Single Site Heterogeneous 0.962 0.85Reactor Blend PE 132I Dow 10.0 HP-LDPE None High Pressure Heterogeneous0.921 0.22 Affinity PL1880 Dow 4.5 ULDPE Octene Single Site Homogeneous0.902 1.0  IP1065 Ingenia 1.8 LLDPE carrier — — — 0.920 2-10 MI carrierCore-Layer (C); Extruder E_(B) Dowlex Dow 68.70 LLDPE OcteneZeigler-Natta Heterogeneous 0.917 0.50 XUS61528.45 PE 662I Dow 30.0HP-LDPE None High Pressure Heterogeneous 0.919 0.50 IP1065 Ingenia 1.3LLDPE carrier — — — 0.920 2-10 MI carrier

EXAMPLE 5

Layers of the Multi-layer Film 5 are prepared with the resins andadditives shown in Table 5.

TABLE 5 Formulation for Multi-layer Film 5 Resin Resin Grade/ Weight %Polymer Catalyst in Density Melt-index Trade Name* Supplier of LayerType Comonomer Resin Manufacture MWD/SCBD g/cm³ deci g/min Inner & OuterSealant-Layer (A & E); Extruder E_(A) Elite 5400G Dow 92.5 LLDPE OcteneSingle Site Heterogeneous 0.916 1.0  Reactor Blend IP1065 Ingenia 3.0LLDPE carrier — — — 0.920 2-10 MI carrier IT 719 Ingenia 2.5 LLDPEcarrier — — — 1.140 2-10 MI carrier IP1142 Ingenia 2.0 LLDPE carrier — —— 0.930 2-10 MI carrier First & Second Interposed-Layer (B & D);Extruder E_(C) Elite 5960G Dow 83.70 HDPE None Single Site Heterogeneous0.962 0.85 Reactor Blend PE 132I Dow 10.0 HP-LDPE None High PressureHeterogeneous 0.921 0.22 Affinity PL1880 Dow 4.5 ULDPE Octene SingleSite Homogeneous 0.902 1.0  IP1065 Ingenia 1.8 LLDPE carrier — — — 0.9202-10 MI carrier Core-Layer (C); Extruder E_(B) Dowlex Dow 68.70 LLDPEOctene Zeigler-Natta Heterogeneous 0.917 0.50 XUS61528.45 PE 662I Dow30.0 HP-LDPE None High Pressure Heterogeneous 0.919 0.50 IP1065 Ingenia1.3 LLDPE carrier — — — 0.920 2-10 MI carrier

EXAMPLE 6

Layers of the Multi-layer Film 6 are prepared with the resins andadditives shown in Table 6.

TABLE 6 Formulation for Multi-layer Film 6 Resin Resin Grade/ Weight %Polymer Catalyst in Density Melt-index Trade Name* Supplier of LayerType Comonomer Resin Manufacture MWD/SCBD g/cm³ deci g/min Inner & OuterSealant-Layer (A & E); Extruder E_(A) Elite 5400G Dow 88.5 LLDPE OcteneSingle Site Heterogeneous 0.916 1.0  Reactor Blend Engage 8150 Dow 4.0ULDPE Octene Single Site Homogeneous 0.868 0.50 IP1065 Ingenia 3.0 LLDPEcarrier — — — 0.920 2-10 MI carrier IT 719 Ingenia 2.5 LLDPE carrier — —— 1.140 2-10 MI carrier IP1142 Ingenia 2.0 LLDPE carrier — — — 0.9302-10 MI carrier First & Second Interposed-Layer (B & D); Extruder E_(C)Elite 5960G Dow 83.70 HDPE None Single Site Heterogeneous 0.962 0.85Reactor Blend PE 132I Dow 10.0 HP-LDPE None High Pressure Heterogeneous0.921 0.22 Affinity PL1880 Dow 4.5 ULDPE Octene Single Site Homogeneous0.902 1.0  IP1065 Ingenia 1.8 LLDPE carrier — — — 0.920 2-10 MI carrierCore-Layer (C); Extruder E_(B) Dowlex Dow 68.70 LLDPE OcteneZeigler-Natta Heterogeneous 0.917 0.50 XUS61528.45 PE 662I Dow 30.0HP-LDPE None High Pressure Heterogeneous 0.919 0.50 IP1065 Ingenia 1.3LLDPE carrier — — — 0.920 2-10 MI carrier

EXAMPLE 7

Layers of the Multi-layer Film 7 are prepared with the resins andadditives shown in Table 7.

TABLE 7 Formulation for Multi-layer Film 7 Weight Catalyst Resin ResinGrade/ % of Polymer Used for Resin Density Melt-index Trade Name*Supplier Layer Type Comonomer Manufacture MWD/SCBD g/cm³ deci g/minInner & Outer Sealant-Layer (A & E); Extruder E_(A) Surpass FPs016C Nova89.9 LLDPE Octene Single Site Homogeneous 0.916 0.65 Engage 8150 Dow 4.0ULDPE Octene Single Site Homogeneous 0.868 0.50 IP1065 Ingenia 3.0 LLDPEcarrier — — — 0.920 2-10 MI carrier IT 719 Ingenia 2.0 LLDPE carrier — —— 1.140 2-10 MI carrier IP1142 Ingenia 1.2 LLDPE carrier — — — 0.9302-10 MI carrier First & Second Interposed-Layer (B & D); Extruder E_(C)Sclair 19C Nova 88.20 HDPE None Ziegler-Natta Heterogeneous 0.954 0.95Elvax 3135X DuPont 10.0 EVA Vinyl acetate High Pressure Heterogeneous0.930 0.35 IP1065 Ingenia 1.8 LLDPE carrier — — — 0.920 2-10 MI carrierCore-Layer (C); Extruder E_(B) Surpass FPs016C Nova 68.70 LLDPE OcteneSingle Site Homogeneous 0.916 0.65 Elvax 3135X DuPont 30 EVA Vinylacetate High Pressure Heterogeneous 0.930 0.35 IP1065 Ingenia 1.8 LLDPEcarrier — — — 0.920 2-10 MI carrier

EXAMPLE 8

Layers of the Multi-layer Film 8 are prepared with the resins andadditives shown in Table 8.

TABLE 8 Formulation for Multi-layer Film 8 Melt- Weight Catalyst Resinindex Resin Grade/ % of Polymer Used for Resin Density deci Trade Name*Supplier Layer Type Comonomer Manufacture MWD/SCBD g/cm³ g/min Inner &Outer Sealant-Layer (A & E); Extruder E_(A) Marflex D143 ChevronPhillips89.5 LLDPE Hexene Single Site Homogeneous 0.916 1.40 Engage 8150 Dow 4.0ULDPE Octene Single Site Homogeneous 0.868 0.50 IP1065 Ingenia 3.0 LLDPEcarrier — — — 0.920 2-10 MI carrier IT 719 Ingenia 2.5 LLDPE carrier — —— 1.140 2-10 MI carrier IP1142 Ingenia 1.0 LLDPE carrier — — — 0.9302-10 MI carrier First & Second Interposed-Layer (B & D); Extruder E_(C)Sclair 19C Nova 88.20 HDPE None Ziegler-Natta Heterogeneous 0.954 0.95Elvax 3135X DuPont 10.0 EVA Vinyl acetate High Pressure Heterogeneous0.930 0.35 IP1065 Ingenia 1.8 LLDPE carrier — — — 0.920 2-10 MI carrierCore-Layer (C); Extruder E_(B) Marflex D143 ChevronPhillips 68.7 LLDPEHexene Single Site Homogeneous 0.916 1.40 Elvax 3135X DuPont 30 EVAVinyl acetate High Pressure Heterogeneous 0.930 0.35 IP1065 Ingenia 1.3LLDPE carrier — — — 0.920 2-10 MI carrier

EXAMPLE 9

Layers of the Multi-layer Film 9 are prepared with the resins andadditives shown in Table 9.

TABLE 9 Formulation for Multi-layer Film 9 Melt- Weight Catalyst Resinindex Resin Grade/ % of Polymer Used for Resin Density deci Trade Name*Supplier Layer Type Comonomer Manufacture MWD/SCBD g/cm³ g/min Inner &Outer Sealant-Layer (A & E); Extruder E_(A) Surpass FPs016C Nova 94.1LLDPE Octene Single Site Homogeneous 0.916 0.65 IP1065 Ingenia 3.0 LLDPEcarrier — — — 0.920 2-10 MI carrier IT 719 Ingenia 1.7 LLDPE carrier — —— 1.140 2-10 MI carrier IP1142 Ingenia 1.2 LLDPE carrier — — — 0.9302-10 MI carrier First & Second Interposed-Layer (B & D); Extruder E_(C)Sclair 19C Nova 88.20 HDPE None Ziegler-Natta Heterogeneous 0.954 0.95Elvax 3135X DuPont 10.0 EVA Vinyl acetate High Pressure Heterogeneous0.930 0.35 IP1065 Ingenia 1.8 LLDPE carrier — — — 0.920 2-10 MI carrierCore-Layer (C); Extruder E_(B) Surpass FPs016C Nova 68.7 LLDPE OcteneSingle Site Homogeneous 0.916 0.65 Elvax 3135X DuPont 30.0 EVA Vinylacetate High Pressure Heterogeneous 0.930 0.35 IP1065 Ingenia 1.3 LLDPEcarrier — — — 0.920 2-10 MI carrier

EXAMPLE 10

Layers of the Multi-layer Film 10 are prepared with the resins andadditives shown in Table 10.

TABLE 10 Formulation for Multi-layer Film 10 Melt- Weight Catalyst Resinindex Resin Grade/ % of Polymer Used for Resin Density deci Trade Name*Supplier Layer Type Comonomer Manufacture MWD/SCBD g/cm³ g/min Inner &Outer Sealant-Layer (A & E); Extruder E_(A) Marflex D143 ChevronPhillips94.3 LLDPE Hexene Single Site Homogeneous 0.916 1.40 IP1065 Ingenia 3.0LLDPE carrier — — — 0.920 2-10 MI carrier IT 719 Ingenia 1.7 LLDPEcarrier — — — 1.140 2-10 MI carrier IP1142 Ingenia 1.0 LLDPE carrier — —— 0.930 2-10 MI carrier First & Second Interposed-Layer (B & D);Extruder E_(C) Sclair 19C Nova 88.20 HDPE None Ziegler-NattaHeterogeneous 0.954 0.95 Elvax 3135X DuPont 10.0 EVA Vinyl acetate HighPressure Heterogeneous 0.930 0.35 IP1065 Ingenia 1.8 LLDPE carrier — — —0.920 2-10 MI carrier Core-Layer (C); Extruder E_(B) Marflex D143ChevronPhillips 68.70 LLDPE Hexene Single Site Homogeneous 0.916 1.40Elvax 3135X DuPont 30.0 EVA Vinyl acetate High Pressure Heterogeneous0.930 0.35 IP1065 Ingenia 1.3 LLDPE carrier — — — 0.920 2-10 MI carrier

EXAMPLE 11

Layers of the Multi-layer Film 11 are prepared with the resins andadditives shown in Table 11.

TABLE 11 Formulation for Multi-layer Film 11 Resin Resin Grade/ Weight %Polymer Catalyst in Density Melt-index Trade Name* Supplier of LayerType Comonomer Resin Manufacture MWD/SCBD g/cm³ deci g/min Inner & OuterSealant-Layer (A & E); Extruder E_(A) Elite 5400G Dow 88.50 LLDPE OcteneSingle Site Heterogeneous 0.916 1.0  Reactor Blend Engage 8150 Dow 4.00ULDPE Octene Single Site Homogeneous 0.868 0.50 IP1065 Ingenia 3.00LLDPE carrier — — — 0.920 2-10 MI carrier IT 719 Ingenia 2.50 LLDPEcarrier — — — 1.140 2-10 MI carrier IP1142 Ingenia 2.00 LLDPE carrier —— — 0.930 2-10 MI carrier First & Second Interposed-Layer (B & D);Extruder E_(C) Elite 5960G Dow 83.70 HDPE None Single Site Heterogeneous0.962 0.85 Reactor Blend PE 662I Dow 10.0 HP-LDPE None High PressureHeterogeneous 0.919 0.50 Engage 8150 Dow 4.5 ULDPE Octene Single SiteHomogeneous 0.868 0.50 IP1065 Ingenia 1.8 LLDPE carrier — — — 0.920 2-10MI carrier Core-Layer (C); Extruder E_(B) Dowlex Dow 68.70 LLDPE OcteneZeigler-Natta Heterogeneous 0.917 0.50 XUS61528.45 PE 132I Dow 30.0HP-LDPE None High Pressure Heterogeneous 0.921 0.22 IP1065 Ingenia 1.3LLDPE carrier — — — 0.920 2-10 MI carrier

EXAMPLE 12

Layers of the Multi-layer Film 12 are prepared with the resins andadditives shown in Table 12.

TABLE 12 Formulation for Multi-layer Film 12 Resin Resin Grade/ Weight %Polymer Catalyst in Density Melt-index Trade Name* Supplier of LayerType Comonomer Resin Manufacture MWD/SCBD g/cm³ deci g/min Inner & OuterSealant-Layer (A & E); Extruder E_(A) Elite 5400G Dow 88.50 LLDPE OcteneSingle Site Heterogeneous 0.916 1.0  Reactor Blend Engage 8150 Dow 4.00ULDPE Octene Single Site Homogeneous 0.868 0.50 IP1065 Ingenia 1.50LLDPE carrier — — — 0.920 2-10 MI carrier IP1061A Ingenia 1.50 LLDPEcarrier — — — 0.920 2-10 MI carrier IT 719 Ingenia 2.50 LLDPE carrier —— — 1.140 2-10 MI carrier IP1142 Ingenia 2.00 LLDPE carrier — — — 0.9302-10 MI carrier First & Second Interposed-Layer (B & D); Extruder E_(C)Elite 5960G Dow 83.70 HDPE None Single Site Heterogeneous 0.962 0.85Reactor Blend PE 662I Dow 10.0 HP-LDPE None High Pressure Heterogeneous0.919 0.50 Engage 8150 Dow 4.5 ULDPE Octene Single Site Homogeneous0.868 0.50 IP1065 Ingenia 0.8 LLDPE carrier — — — 0.920 2-10 MI carrierIP1061A Ingenia 1.0 LLDPE carrier — — — 0.920 2-10 MI carrier Core-Layer(C); Extruder E_(B) Dowlex Dow 68.70 LLDPE Octene Zeigler-NattaHeterogeneous 0.917 0.50 XUS61528.45 PE 132I Dow 30.0 HP-LDPE None HighPressure Heterogeneous 0.921 0.22 IP1065 Ingenia 1.3 LLDPE carrier — — —0.920 2-10 MI carrier

EXAMPLE 13

Layers of the Multi-layer Film 13 are prepared with the resins andadditives shown in Table 13.

TABLE 13 Formulation for Multi-layer Film 13 Resin Resin Grade/ Weight %Polymer Catalyst in Density Melt-index Trade Name* Supplier of LayerType Comonomer Resin Manufacture MWD/SCBD g/cm³ deci g/min Inner & OuterSealant-Layer (A & E); Extruder E_(A) Elite 5400G Dow 88.50 LLDPE OcteneSingle Site Heterogeneous 0.916 1.0  Reactor Blend Engage 8150 Dow 4.00ULDPE Octene Single Site Homogeneous 0.868 0.50 IP1061A Ingenia 3.0LLDPE carrier — — — 0.920 2-10 MI carrier IT 719 Ingenia 2.50 LLDPEcarrier — — — 1.140 2-10 MI carrier IP1142 Ingenia 2.00 LLDPE carrier —— — 0.930 2-10 MI carrier First & Second Interposed-Layer (B & D);Extruder E_(C) Elite 5960G Dow 84.00 HDPE None Single Site Heterogeneous0.962 0.85 Reactor Blend PE 662I Dow 10.0 HP-LDPE None High PressureHeterogeneous 0.919 0.50 Engage 8150 Dow 4.5 ULDPE Octene Single SiteHomogeneous 0.868 0.50 IP1061A Ingenia 1.5 LLDPE carrier — — — 0.9202-10 MI carrier Core-Layer (C); Extruder E_(B) Dowlex Dow 69.00 LLDPEOctene Zeigler-Natta Heterogeneous 0.917 0.50 XUS61528.45 PE 132I Dow30.0 HP-LDPE None High Pressure Heterogeneous 0.921 0.22 IP1061A Ingenia1.0 LLDPE carrier — — — 0.920 2-10 MI carrier

EXAMPLE 14

Layers of the Multi-layer Film 14 are prepared with the resins andadditives shown in Table 14.

TABLE 14 Formulation for Multi-layer Film 14 Resin Resin Grade/ Weight %Polymer Catalyst in Density Melt-index Trade Name* Supplier of LayerType Comonomer Resin Manufacture MWD/SCBD g/cm³ deci g/min Inner & OuterSealant-Layer (A & E); Extruder E_(A) Exceed 1012CJ Exxon- 94.5 LLDPEHexene Single Site Heterogeneous 0.912 1.0  Mobil Reactor Blend IP1065Ingenia 3.0 LLDPE carrier — — — 0.920 2-10 MI carrier IT 719 Ingenia 1.3LLDPE carrier — — — 1.140 2-10 MI carrier IP1142 Ingenia 1.2 LLDPEcarrier — — — 0.930 2-10 MI carrier First & Second Interposed-Layer (B &D); Extruder E_(C) Sclair 19C Nova 88.20 HDPE None Zeigler-NattaHeterogeneous 0.958 0.95 PE 662I Dow 10.0 HP-LDPE None High PressureHeterogeneous 0.919 0.50 IP1065 Ingenia 1.8 LLDPE carrier — — — 0.9202-10 MI carrier Core-Layer (C); Extruder E_(B) Dowlex Dow 68.70 LLDPEOctene Zeigler-Natta Heterogeneous 0.917 0.50 XUS61528.45 PE 132I Dow30.0 HP-LDPE None High Pressure Heterogeneous 0.921 0.22 IP1065 Ingenia1.3 LLDPE carrier — — — 0.920 2-10 MI carrier

EXAMPLE 15

Layers of the Multi-layer Film 15 are prepared with the resins andadditives shown in Table 15.

TABLE 15 Formulation for Multi-layer Film 15 Resin Resin Grade/ Weight %Polymer Catalyst in Density Melt-index Trade Name* Supplier of LayerType Comonomer Resin Manufacture MWD/SCBD g/cm³ deci g/min Inner & OuterSealant-Layer (A & E); Extruder E_(A) Exceed 1012CJ Exxon- 83.8 LLDPEHexene Single Site Heterogeneous 0.912 1.0  Mobil Reactor Blend PE 132IDow 10.0 HP-LDPE None High Pressure Heterogeneous 0.921 0.22 IP1065Ingenia 3.0 LLDPE carrier — — — 0.920 2-10 MI carrier IT 719 Ingenia 2.0LLDPE carrier — — — 1.140 2-10 MI carrier IP1142 Ingenia 1.2 LLDPEcarrier — — — 0.930 2-10 MI carrier First & Second Interposed-Layer (B &D); Extruder E_(C) Sclair 19C Nova 88.20 HDPE None Zeigler-NattaHeterogeneous 0.958 0.95 PE 132I Dow 10.0 HP-LDPE None High PressureHeterogeneous 0.921 0.22 IP1065 Ingenia 1.8 LLDPE carrier — — — 0.9202-10 MI carrier Core-Layer (C); Extruder E_(B) Dowlex Dow 83.70 LLDPEOctene Zeigler-Natta Heterogeneous 0.917 0.50 XUS61528.45 PE 132I Dow15.0 HP-LDPE None High Pressure Heterogeneous 0.921 0.22 IP1065 Ingenia1.3 LLDPE carrier — — — 0.920 2-10 MI carrier

EXAMPLE 16

Layers of the Multi-layer Film i6 are prepared with the resins andadditives shown in Table 16.

TABLE 16 Formulation for Multi-layer Film 16 Resin Resin Grade/ Weight %Polymer Catalyst in Density Melt-index Trade Name* Supplier of LayerType Comonomer Resin Manufacture MWD/SCBD g/cm³ deci g/min Inner & OuterSealant-Layer (A & E); Extruder E_(A) Exceed 1012CJ Exxon- 92.5 LLDPEHexene Single Site Heterogeneous 0.912 1.0  Mobil Reactor Blend IP1065Ingenia 4.0 LLDPE carrier — — — 0.920 2-10 MI carrier IP1051 Ingenia 1.5LLDPE carrier — — — 1.000 2-10 MI carrier IP1142 Ingenia 2.0 LLDPEcarrier — — — 0.930 2-10 MI carrier First & Second Interposed-Layer (B &D); Extruder E_(C) Sclair 19C Nova 83.20 HDPE None Zeigler-NattaHeterogeneous 0.958 0.95 PE 662I Dow 15.0 HP-LDPE None High PressureHeterogeneous 0.919 0.50 IP1065 Ingenia 1.8 LLDPE carrier — — — 0.9202-10 MI carrier Core-Layer (C); Extruder E_(B) Dowlex Dow 73.70 LLDPEOctene Zeigler-Natta Heterogeneous 0.917 0.50 XUS61528.45 PE 662I Dow25.0 HP-LDPE None High Pressure Heterogeneous 0.919 0.50 IP1065 Ingenia1.3 LLDPE carrier — — — 0.920 2-10 MI carrier

EXAMPLE 17

Layers of the Multi-layer Film 17 are prepared with the resins andadditives shown in Table 17.

TABLE 17 Formulation for Multi-layer Film 17 Resin Resin Grade/ Weight %Polymer Catalyst in Density Melt-index Trade Name* Supplier of LayerType Comonomer Resin Manufacture MWD/SCBD g/cm³ deci g/min Inner & OuterSealant-Layer (A & E); Extruder E_(A) Enable 2005 CE Exxon- 95 LLDPEHexene Single Site Heterogeneous 0.920 0.5 Mobil Reactor BlendPetrothene NA960 Lyondell- 5 HP-LDPE None High Pressure Heterogeneous0.919 1.0 Basell First & Second Interposed-Layer (B & D); Extruder E_(C)Sclair 19C Nova 90 HDPE None Zeigler-Natta Heterogeneous 0.958 0.95Petrothene NA960 Lyondell- 10 HP-LDPE None High Pressure Heterogeneous0.919 1.0 Basell Core-Layer (C); Extruder E_(B) Enable 2005 CE Exxon- 85LLDPE Hexene Single Site Heterogeneous 0.920 0.50 Mobil Reactor BlendAffinity PL1880 Dow 15 ULDPE Octene Single Site Homogeneous 0.902 1.0

1. A multi-layer film for making pouches for containing flowable materials, said multi-layer film comprising the following layers in order, from an at least one inner sealant-layer to an at least one outer sealant-layer: (A) said at least one inner sealant-layer comprising polyethylene that is selected from the group consisting of: (i) an at least one low-density ethylene-alpha-olefin copolymer, (ii) a blend of said at least one low-density ethylene-alpha-olefin copolymer and an at least one ethylene homopolymer, wherein said ethylene homopolymer is made in a high-pressure polymerization process; and (iii) a blend of said at least one low-density ethylene-alpha-olefin copolymer and an at least one ethylene copolymer, wherein said ethylene copolymer is made in a high-pressure polymerization process; (B) a first at least one interposed layer adjacent to said at least one inner sealant-layer, said first at least one interposed layer comprising: (i) an at least one high-density polyethylene, or a blend of said at least one high-density polyethylene and at least one ethylene-alpha-olefin copolymer; (ii) optionally, an ethylene homopolymer made in a high-pressure polymerization process; (iii) optionally, an ethylene copolymer made in a high pressure polymerization process; and (iv) optionally, a second ethylene-alpha-olefin copolymer that is not the same as said at least one ethylene-alpha-olefin copolymer in (B)(i); wherein the centerline of said first at least one interposed layer is closer to the centerline of said at least one inner sealant-layer than to the centerline of said multi-layer film; (C) at least one core layer, adjacent to said first at least one interposed layer, said at least one core layer comprising polyethylene that is selected from the group consisting of: (i) at least one low-density ethylene-alpha olefin copolymer, (ii) a blend of said at least one low-density ethylene-alpha-olefin copolymer and an at least one ethylene homopolymer, wherein said ethylene homopolymer is made in a high-pressure polymerization process; and (iii) a blend of said at least one low-density ethylene-alpha-olefin copolymer and an at least one ethylene copolymer, wherein said ethylene copolymer is made in a high-pressure polymerization process; (D) a second at least one interposed layer adjacent to said at least one core layer, said second at least one interposed layer comprising: (i) an at least one high-density polyethylene, or a blend of said at least one high-density polyethylene and at least one ethylene-alpha-olefin copolymer; (ii) optionally, an ethylene homopolymer made in a high-pressure polymerization process; (iii) optionally, an ethylene copolymer made in a high pressure polymerization process; and (iv) optionally, a second ethylene-alpha-olefin copolymer that is not the same as said at least one ethylene-alpha-olefin copolymer in (D)(i); wherein the centerline of said second at least one interposed layer is closer to the centerline of said at least one outer sealant-layer than to the centerline of said multi-layer film; and (E) said at least one outer sealant-layer, comprising polyethylene that is selected from the group consisting of: (i) an at least one low-density ethylene-alpha-olefin copolymer, (ii) a blend of said at least one low-density ethylene-alpha-olefin copolymer and an at least one ethylene homopolymer, wherein said ethylene homopolymer is made in a high-pressure polymerization process; and (iii) a blend of said at least one low-density ethylene-alpha-olefin copolymer and an at least one ethylene copolymer, wherein said ethylene copolymer is made in a high-pressure polymerization process; wherein said multi-layer film thickness is in the range of from about 35 microns to about 66 microns; wherein a combined thickness of said first at least one interposed layer and said second at least one interposed layer is in the range of from about 10% to about 27% of the total thickness of said multi-layer film; wherein a combined thickness of said inner sealant-layer and said outer sealant-layer is in the range of from about 10% to about 27% of the total thickness of said multi-layer film; and wherein said at least one high-density polyethylene in said first at least one interposed layer and said second at least one interposed layer has a density of at least of about 0.950 g/cm³ and a melt-index of less than 1.05 dg/min.
 2. The multi-layer film as recited in claim 1, wherein said multi-layer film thickness is in the range of from about 38 microns to about 63 microns.
 3. The multi-layer film as recited in claim 1, wherein said multi-layer film thickness is in the range of from about 44 microns to about 60 microns.
 4. The multi-layer film as recited in claim 1, wherein said multi-layer film thickness is in the range of from about 47 microns to about 59 microns.
 5. The multi-layer film as recited in claim 1, wherein said multi-layer film thickness is selected from the group consisting of about 45 microns, about 46 microns, about 47 microns, about 48 microns, about 49 microns, about 50 microns, about 51 microns, about 52 microns, about 53 microns, about 54 microns, about 55 microns, about 56 microns, about 57 microns and about 58 microns.
 6. The multi-layer film as recited in claim 1, wherein said at least one inner sealant-layer comprises: (i) from about 80 to about 98 parts by weight of said low-density copolymer of ethylene and an at least one C₄-C₁₀ alpha-olefin manufactured in a polymerization process using a single-site polymerization catalyst, with a density in the range of from about 0.909 to about 0.935 g/cm³ and a melt-index in the range of from about 0.5 to about 1.5, and (ii) from about 0 to about 15 parts by weight of an additional at least one low-density copolymer of ethylene and an at least one C₄-C₁₀ alpha-olefin, which is an ultra-low density copolymer of ethylene and at least one C₄-C₁₀ alpha-olefin manufactured in a polymerization process using a single-site polymerization catalyst, with a density in the range of from about 0.859 to about 0.888 g/cm³ and a melt-index in the range of from about 0.4 to about 0.6 dg/min.
 7. The multi-layer film as recited in claim 1, wherein said at least one outer sealant-layer comprises: (i) from about 80 to about 98 parts by weight of said low-density copolymer of ethylene and an at least one C₄-C₁₀ alpha-olefin manufactured in a polymerization process using a single-site polymerization catalyst, with a density in the range of from about 0.909 to about 0.935 g/cm³ and a melt-index in the range of from about 0.5 to about 1.5 dg/min, and (ii) from about 0 to about 15 parts by weight of an additional at least one low-density copolymer of ethylene and an at least one C₄-C₁₀ alpha-olefin, which is an ultra-low density copolymer of ethylene and at least one C₄-C₁₀ alpha-olefin manufactured in a polymerization process using a single-site polymerization catalyst, with a density in the range of from about 0.859 to about 0.888 g/cm³ and a melt-index in the range of from about 0.4 to about 0.6 dg/min.
 8. The multi-layer film as recited in claim 1, wherein said at least one inner sealant-layer further comprises from about 0 to about 15 parts by weight of said at least one ethylene homopolymer manufactured in a high pressure polymerization process or said at least one ethylene copolymer manufactured in a high pressure polymerization process, wherein said at least one ethylene homopolymer has a density in the range of from about 0.918 to about 0.923 g/cm³ and a melt-index in the range of from about 0.1 to 1.1 dg/min, and said at least one ethylene copolymer has a density in the range of from about 0.930 to about 0.960 g/cm³ and a melt-index in the range of from about 0.1 to about 10 dg/min.
 9. The multi-layer film as recited in claim 1, wherein said at least one outer sealant-layer further comprises from 0 to about 15 parts by weight of said at least one ethylene homopolymer manufactured in a high pressure polymerization process or said at least one ethylene copolymer manufactured in a high pressure polymerization process, wherein the ethylene homopolymer has a density in the range of from about 0.918 to about 0.923 g/cm³ and a melt-index in the range of from about 0.1 to 1.1 dg/min, and the ethylene copolymer has a density in the range of from about 0.930 to about 0.960 g/cm³ and a melt-index in the range of from about 0.1 to about 10 dg/min.
 10. The multi-layer film of claim 6, wherein said low-density copolymer of ethylene and at least one C₄-C₁₀ alpha-olefin, or said at least one ultra-low density copolymer of ethylene and at least one C₄-C₁₀ alpha-olefin is selected from ethylene/butene-1 copolymers, ethylene/hexene-1 copolymers, ethylene/octene-1 copolymers, ethylene/octene-1/butene-1 terpolymers and ethylene/hexene-1/butene-1 terpolymers.
 11. The multi-layer film as recited in claim 1, wherein, in said first at least one interposed layer or in said at least second interposed layer: (i) said at least one high-density polyethylene is in the range of from about 78 to about 100 parts by weight of said first at least one interposed layer or of said second at least one interposed layer, wherein said at least one high-density polye-thylene that is manufactured in a polymerization process using a single-site polymerization catalyst or a Ziegler-Natta catalyst, wherein said at least one high-density polyethylene has a density greater than about 0.950 g/cm³ but less than about 0.970 g/cm³ and a melt-index in the range of from about 0.75 to about 10.5 dg/min, (ii) said at least one ethylene-alpha olefin copolymer is in the range from 0 to about 15 parts by weight of said first at least one interposed layer or of said second at least one interposed layer, wherein said at least one C₄-C₁₀ alpha-olefin is an ultra-low density copolymer of ethylene and at least one C₄-C₁₀ alpha-olefin manufactured in a polymerization process using a single-site polymerization catalyst, with a density in the range of from about 0.859 to about 0.905 g/cm³ and a melt-index in the range of from about 0.4 to about 1.1 dg/min, (iii) said at least one optional ethylene homopolymer or copolymer, manufactured in a high pressure polymerization process, is in the range of from about 0 parts to 15 parts by weight of said first at least one interposed layer or of said second at least on interposed layer, wherein the ethylene homopolymer has a density in the range of from about 0.918 to about 0.923 g/cm³ and a melt-index in the range of from about 0.1 to 1.1 dg/min, and the ethylene copolymer has a density in the range 0.930 to about 0.960 g/cm³ and a melt-index in the range of from about 0.1 to about 10 dg/min, and (iv) said at least one additional ethylene-alpha-olefin copolymer is in the range of from about 0 parts to 15 parts by weight, and can be manufactured in a polymerization process using either a single-site or Zeigler-Natta polymerization catalyst, wherein said copolymer has a density in the range of from about 0.909 to about 0.935 g/cm³ and a melt-index in the range of from about 0.5 to about 1.5 dg/min.
 12. The multi-layer film of claim 11, wherein said low-density copolymer of ethylene and at least one C₄-C₁₀ alpha-olefin, or said at least one ultra-low density copolymer of ethylene and at least one C₄-C₁₀ alpha-olefin is selected from ethylene/butene-1 copolymers, ethylene/hexene-1 copolymers, ethylene/octene-1 copolymers, ethylene/octene-1/butene-1 terpolymers and ethylene/hexene-1/butene-1 terpolymers.
 13. The multi-layer film as recited in claim 1, wherein, in said at least one core layer: (i) said at least one low density ethylene-alpha olefin copolymer is in the range from 35 to about 85 parts by weight of said at least one core layer, and can be manufactured in a polymerization process using either a single-site or Zeigler-Natta polymerization catalyst, wherein said copolymer has a density in the range of from about 0.909 to about 0.935 g/cm³ and a melt-index in the range of from about 0.5 to about 1.5 dg/min; (ii) from 0 to about 15 parts by weight of an additional at least one low-density copolymer of ethylene and an at least one C₄-C₁₀ alpha-olefin, which is an ultra-low density copolymer of ethylene and at least one C₄-C₁₀ alpha-olefin manufactured in a polymerization process using a single-site polymerization catalyst, with a density in the range of from about 0.859 to about 0.905 g/cm³ and a melt-index in the range of from about 0.4 to about 1.1 dg/min; and (iii) said at least one low-density ethylene homopolymer or copolymer, made in a high pressure polymerization process, is in the range of from about 10 parts to 50 parts by weight of said at least one core layer, wherein the ethylene homopolymer has a density in the range of from about 0.918 to about 0.923 g/cm³ and a melt-index in the range of from about 0.1 to 1.1 dg/min, and the ethylene copolymer has a density in the range of from about 0.930 to about 0.960 g/cm³ and a melt-index in the range of from about 0.1 to about 10 dg/min.
 14. The multi-layer film of claim 12, wherein said low-density copolymer of ethylene and at least one C₄-C₁₀ alpha-olefin, or said at least one ultra-low density copolymer of ethylene and at least one C₄-C₁₀ alpha-olefin is selected from ethylene/butene-1 copolymers, ethylene/hexene-1 copolymers, ethylene/octene-1 copolymers, ethylene/octene-1/butene-1 terpolymers and ethylene/hexene-1/butene-1 terpolymers.
 15. The process for making pouches filled with a flowable material, using a vertical form, fill and seal apparatus, wherein each pouch is made from a flat web of film by the following steps: (I) forming a tubular film therefrom with a longitudinal seal and subsequently flattening said tubular film at a first position; (II) transversely heat-sealing said tubular film at the flattened position; (III) filling said tubular film with a predetermined quantity of flowable material above said first position; (IV) flattening said tubular film above the predetermined quantity of flowable material at a second position; and (V) transversely heat sealing said tubular film at said second position, wherein said pouches are made from a flat web of film made from a multi-layer film, comprising the following layers in order of an at least one inner sealant-layer to an at least one outer sealant-layer: (A) said at least one inner sealant-layer comprising polyethylene that is selected from the group consisting of: (i) an at least one low-density ethylene-alpha-olefin copolymer, (ii) a blend of said at least one low-density ethylene-alpha-olefin copolymer and an at least one ethylene homopolymer, wherein said ethylene homopolymer is made in a high-pressure polymerization process; and (iii) a blend of said at least one low-density ethylene-alpha-olefin copolymer and an at least one ethylene copolymer, wherein said ethylene copolymer is made in a high-pressure polymerization process; (B) a first at least one interposed layer adjacent to said at least one inner sealant-layer, said first at least one interposed layer comprising: (i) an at least one high-density polyethylene, or a blend of said at least one high-density polyethylene and at least one ethylene-alpha-olefin copolymer; (ii) optionally, an ethylene homopolymer made in a high-pressure polymerization process; (iii) optionally, an ethylene copolymer made in a high pressure polymerization process; and (iv) optionally, a second ethylene-alpha-olefin copolymer that is not the same as said at least one ethylene-alpha-olefin copolymer in (B)(i); wherein the centerline of said first at least one interposed layer is closer to the centerline of said at least one inner sealant-layer than to the centerline of said multi-layer film; (C) at least one core layer, adjacent to said first at least one interposed layer, said at least one core layer comprising polyethylene that is selected from the group consisting of: (i) at least one low-density ethylene-alpha olefin copolymer, (ii) a blend of said at least one low-density ethylene-alpha-olefin copolymer and an at least one ethylene homopolymer, wherein said ethylene homopolymer is made in a high-pressure polymerization process; and (iii) a blend of said at least one low-density ethylene-alpha-olefin copolymer and an at least one ethylene copolymer, wherein said ethylene copolymer is made in a high-pressure polymerization process; (D) a second at least one interposed layer adjacent to said at least one core layer, said second at least one interposed layer comprising: (i) an at least one high-density polyethylene, or a blend of said at least one high-density polyethylene and at least one ethylene-alpha-olefin copolymer; (ii) optionally, an ethylene homopolymer made in a high-pressure polymerization process; (iii) optionally, an ethylene copolymer made in a high pressure polymerization process; and (iv) optionally, a second ethylene-alpha-olefin copolymer that is not the same as said at least one ethylene-alpha-olefin copolymer in (D)(i); wherein the centerline of said second at least one interposed layer is closer to the centerline of said at least one outer sealant-layer than to the centerline of said multi-layer film; and (E) said at least one outer sealant-layer, comprising polyethylene that is selected from the group consisting of: (i) an at least one low-density ethylene-alpha-olefin copolymer, (ii) a blend of said at least one low-density ethylene-alpha-olefin copolymer and an at least one ethylene homopolymer, wherein said ethylene homopolymer is made in a high-pressure polymerization process; and (iii) a blend of said at least one low-density ethylene-alpha-olefin copolymer and an at least one ethylene copolymer, wherein said ethylene copolymer is made in a high-pressure polymerization process; wherein said multi-layer film thickness is in the range of from about 35 microns to about 66 microns; wherein a combined thickness of said first at least one interposed layer and said second at least one interposed layer is in the range of from about 10% to about 27% of the total thickness of said multi-layer film; wherein a combined thickness of said inner sealant-layer and said outer sealant-layer is in the range of from about 10% to about 27% of the total thickness of said multi-layer film; and wherein said at least one high-density polyethylene in said first at least one interposed layer and said second at least one interposed layer has a density of at least of about 0.950 g/cm³ and a melt-index of less than 1.05 dg/min.
 16. The process as recited in claim 15, wherein said multi-layer film thickness is in the range of from about 38 microns to about 63 microns.
 17. The process as recited in claim 15, wherein said multi-layer film thickness is in the range of from about 44 microns to about 60 microns.
 18. The process as recited in claim 15, wherein said multi-layer film thickness is in the range of from about 47 microns to about 59 microns.
 19. The process as recited in claim 15, wherein said multi-layer film thickness is selected from the group consisting of about 45 microns, about 46 microns, 5 about 47 microns, about 48 microns, about 49 microns, about 50 microns, about 51 microns, about 52 microns, about 53 microns, about 54 microns, about 55 microns, about 56 microns, about 57 microns, and about 58 microns.
 20. The process as recited in claim 15, wherein said at least one inner sealant-layer comprises: (i) from about 80 to about 98 parts by weight of said low-density copolymer of ethylene and an at least one C₄-C₁₀ alpha-olefin manufactured in a polymerization process using a single-site polymerization catalyst, with a density in the range of from about 0.909 to 0.935 g/cm³ and a melt-index in the range of from about 0.5 to about 1.5, and (ii) from about 0 to about 15 parts by weight of an additional at least one low-density copolymer of ethylene and an at least one C₄-C₁₀ alpha-olefin, which is an ultra-low density copolymer of ethylene and at least one C₄-C₁₀ alpha-olefin manufactured in a polymerization process using a single-site polymerization catalyst, with a density in the range of from about 0.859 to about 0.888 g/cm³ and a melt-index in the range of from about 0.4 to about 0.6 dg/min.
 21. The process as recited in claim 15, wherein said at least one outer sealant-layer comprises: (i) from about 80 to about 98 parts by weight of said low-density copolymer of ethylene and an at least one C₄-C₁₀ alpha-olefin manufactured in a polymerization process using a single-site polymerization catalyst, with a density in the range of from about 0.909 to about 0.935 g/cm³ and a melt-index in the range of from about 0.5 to about 1.5, and (ii) from about 0 to about 15 parts by weight of an additional at least one low-density copolymer of ethylene and an at least one C₄-C10 alpha-olefin, which is an ultra-low density copolymer of ethylene and at least one C₄-C₁₀ alpha-olefin manufactured in a polymerization process using a single-site polymerization catalyst, with a density in the range of from about 0.859 to about 0.888 g/cm³and a melt-index in the range of from about 0.4 to about 0.6 dg/min.
 22. The process as recited in claim 15, wherein said at least one inner sealant-layer further comprises from about 0 parts to about 15 parts by weight of said at least one low-density ethylene homopolymer with a density in the range of from about 0.918 to about 0.923 g/cm³ and a melt-index in the range of from about 0.1 to about 1.1 dg/min.
 23. The process as recited in claim 15, wherein said at least one inner sealant-layer further comprises from 0 to about 15 parts by weight of said ethylene copolymer with a density in the range 0.930-0.960 g/cm³ and a melt-index in the range of from about 0.1 to 10 dg/min.
 24. The process as recited in claim 15, wherein said at least one outer sealant-layer further comprises from 0 to 15 parts by weight of said at least one low-density ethylene homopolymer with a density in the range of from about 0.918 to about 0.923 g/cm³ and a melt-index in the range of from about 0.1 to about 1.1 dg/min.
 25. The process as recited in claim 15, wherein said at least one outer sealant-layer further comprises from 0 to about 15 parts by weight of said ethylene copolymer with a density in the range 0.930-0.960 g/cm³ and a melt-index in the range of from about 0.1 to 10 dg/min.
 26. The process of claim 20, wherein said low-density copolymer of ethylene and at least one C₄-C₁₀ alpha-olefin, or said at least one ultra-low density copolymer of ethylene and at least one C₄-C₁₀ alpha-olefin is selected from ethylene/butene-1 copolymers, ethylene/hexene-1 copolymers, ethylene/octene-1 copolymers, ethylene/octene-1/butene-1 terpolymers and ethylene/hexene-1/butene-1 terpolymers.
 27. The process as recited in claim 15, wherein, in said first at least one interposed layer and/or in said second at least one interposed layer: (i) said at least one high-density polyethylene is in the range of from about 78 to about 100 parts by weight of said first at least one interposed layer or of said second at least one interposed layer, wherein said at least one high-density polyethylene that is manufactured in a polymerization process using a single-site polymerization catalyst or a Ziegler-Natta catalyst, wherein said at least one high-density polyethylene has a density greater than 0.950 g/cm³ and a melt-index in the range of from about 0.75 to about 1.05 dg/min, (ii) said at least one ethylene-alpha olefin copolymer is in the range from 0 to about 15 parts by weight of said first at least one interposed layer or of said second at least one interposed layer, wherein said at least one C₄-C₁₀ alpha-olefin is an ultra-low density copolymer of ethylene and at least one C₄-C₁₀ alpha-olefin manufactured in a polymerization process using a single-site polymerization catalyst, with a density in the range of from about 0.859 to about 0.905 g/cm³ and a melt-index in the range of from about 0.4 to about 1.1 dg/min, (iii) said at least one optional ethylene homopolymer or copolymer, manufactured in a high pressure polymerization process, is in the range of from about 0 parts to 15 parts by weight of said first at least one interposed layer or of said second at least on interposed layer, wherein the ethylene homopolymer has a density in the range of from about 0.918 to about 0.923 g/cm³ and a melt-index in the range of from about 0.1 to 1.1 dg/min, and the ethylene copolymer has a density in the range 0.930 to about 0.960g/cm³ and a melt-index in the range of from about 0.1 to about 10 dg/min, and (iv) said at least one additional ethylene-alpha-olefin copolymer is in the range of from about 0 parts to 15 parts by weight, and can be manufactured in a polymerization process using either a single-site or Zeigler-Natta polymerization catalyst, wherein said copolymer has a density in the range of from about 0.909 to about 0.935 g/cm³ and a melt-index in the range of from about 0.5 to about 1.5 dg/min.
 28. The process as recited in claim 27, wherein said low-density copolymer of ethylene and at least one C₄-C₁₀ alpha-olefin, or said at least one ultra-low density copolymer of ethylene and at least one C₄-C₁₀ alpha-olefin is selected from ethylene/butene-1 copolymers, ethylene/hexene-1 copolymers, ethylene/octene-1 copolymers, ethylene/octene-1/butene-1 terpolymers and ethylene/hexene-1/butene-1 terpolymers.
 29. The process as recited in claim 15, wherein, in said at least one core layer: (i) said at least one low density ethylene-alpha olefin copolymer is in the range from 35 to about 85 parts by weight of said at least one core layer, and can be manufactured in a polymerization process using either a single-site or Zeigler-Natta polymerization catalyst, wherein said copolymer has a density in the range of from about 0.909 to about 0.935 g/cm³ and a melt-index in the range of from about 0.5 to about 1.5 dg/min; (ii) from 0 to about 15 parts by weight of an additional at least one low-density copolymer of ethylene and an at least one C₄-C₁₀ alpha-olefin, which is an ultra-low density copolymer of ethylene and at least one C₄-C₁₀ alpha-olefin manufactured in a polymerization process using a single-site polymerization catalyst, with a density in the range of from about 0.859 to about 0.905 g/cm³ and a melt-index in the range of from about 0.4 to about 1.1 dg/min; and (iii) said at least one low-density ethylene homopolymer or copolymer, made in a high pressure polymerization process, is in the range of from about 10 parts to 50 parts by weight of said at least one core layer, wherein the ethylene homopolymer has a density in the range of from about 0.918 to about 0.923 g/cm³ and a melt-index in the range of from about 0.1 to 1.1 dg/min, and the ethylene copolymer has a density in the range of from about 0.930 to about 0.960 g/cm³ and a melt-index in the range of from about 0.1 to about 10 dg/min.
 30. The process of claim 29, wherein said low-density copolymer of ethylene and at least one C₄-C₁₀ alpha-olefin, or said at least one ultra-low density copolymer of ethylene and at least one C₄-C₁₀ alpha-olefin is selected from ethylene/butene-1 copolymers, ethylene/hexene-1 copolymers, ethylene/octene-1 copolymers, ethylene/octene-1/butene-1 terpolymers and ethylene/hexene-1/butene-1 terpolymers.
 31. The multi-layer film of claim 7, wherein said low-density copolymer of ethylene and at least one C₄-C₁₀ alpha-olefin, or said at least one ultra-low density copolymer of ethylene and at least one C₄-C₁₀ alpha-olefin is selected from ethylene/butene-1 copolymers, ethylene/hexene-1 copolymers, ethylene/octene-1 copolymers, ethylene/octene-1/butene-1 terpolymers and ethylene/hexene-1/butene-1 terpolymers.
 32. The process of claim 21, wherein said low-density copolymer of ethylene and at least one C₄-C₁₀ alpha-olefin, or said at least one ultra-low density copolymer of ethylene and at least one C₄-C₁₀ alpha-olefin is selected from ethylene/butene-1 copolymers, ethylene/hexene-1 copolymers, ethylene/octene-1 copolymers, ethylene/octene-1/butene-1 terpolymers and ethylene/hexene-1/butene-1 terpolymers. 